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authorAkshay <[email protected]>2020-10-17 08:04:30 +0100
committerAkshay <[email protected]>2020-10-17 08:04:30 +0100
commit3414053d7cd17b43dd929e4e5fc468d98145e0d5 (patch)
tree7b6ec8cfe18e217343cdd54986d5c179fc9e8098
parent897df34e5e55448ae89fbf1a77533e792e7a5c4e (diff)
update intro, new post: Self-hosting Git!
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diff --git a/docs/index.html b/docs/index.html
index ecc0fce..3ab2ec3 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -28,7 +28,10 @@
28 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 28 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
29 <p> 29 <p>
30 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 30 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
31 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 31 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
32 I also design fonts:
33 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
34 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
32 </p> 35 </p>
33 <p>Send me a mail at [email protected] or a message at [email protected].</p> 36 <p>Send me a mail at [email protected] or a message at [email protected].</p>
34 </div> 37 </div>
@@ -36,6 +39,23 @@
36 <tr> 39 <tr>
37 <td class=table-post> 40 <td class=table-post>
38 <div class="date"> 41 <div class="date">
42 17/10 — 2020
43 </div>
44 <a href="/posts/self-hosting_git" class="post-link">
45 <span class="post-link">Self-hosting Git</span>
46 </a>
47 </td>
48 <td class=table-stats>
49 <span class="stats-number">
50 5.4
51 </span>
52 <span class=stats-unit>min</span>
53 </td>
54 </tr>
55
56 <tr>
57 <td class=table-post>
58 <div class="date">
39 01/09 — 2020 59 01/09 — 2020
40 </div> 60 </div>
41 <a href="/posts/nixOS" class="post-link"> 61 <a href="/posts/nixOS" class="post-link">
diff --git a/docs/index.xml b/docs/index.xml
index d6f1ca7..7e8190c 100644
--- a/docs/index.xml
+++ b/docs/index.xml
@@ -12,6 +12,134 @@
12 <language>en-us</language> 12 <language>en-us</language>
13 <copyright>Creative Commons BY-NC-SA 4.0</copyright> 13 <copyright>Creative Commons BY-NC-SA 4.0</copyright>
14 <item> 14 <item>
15<title>Self-hosting Git</title>
16<description>&lt;p&gt;Earlier this week, I began migrating my repositories from Github to &lt;a href="https://git.zx2c4.com/"&gt;cgit&lt;/a&gt;. If you care at all about big corporates turning open-source into a T-shirt farming service, this is the way to go.&lt;/p&gt;
17&lt;h3 id="offerings"&gt;Offerings&lt;/h3&gt;
18&lt;p&gt;cgit is &lt;em&gt;very&lt;/em&gt; bare bones. It is &lt;a href="https://tools.ietf.org/html/rfc3875"&gt;cgi&lt;/a&gt; web interface interface to git, and nothing more. You may browse repositories, view diffs, commit logs and even clone via http. If you are looking to replace Github with cgit, keep in mind that cgit does not handle issues or pull/merge requests. If people wish to contribute to your work, they would have to send you a patch via email.&lt;/p&gt;
19&lt;h3 id="setup"&gt;Setup&lt;/h3&gt;
20&lt;p&gt;Installing cgit is fairly straightforward, if you would like to compile it from source:&lt;/p&gt;
21&lt;div class="sourceCode" id="cb1"&gt;&lt;pre class="sourceCode sh"&gt;&lt;code class="sourceCode bash"&gt;&lt;span id="cb1-1"&gt;&lt;a href="#cb1-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;# fetch&lt;/span&gt;&lt;/span&gt;
22&lt;span id="cb1-2"&gt;&lt;a href="#cb1-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="fu"&gt;git&lt;/span&gt; clone https://git.zx2c4.com &lt;span class="kw"&gt;&amp;amp;&amp;amp;&lt;/span&gt; &lt;span class="bu"&gt;cd&lt;/span&gt; cgit&lt;/span&gt;
23&lt;span id="cb1-3"&gt;&lt;a href="#cb1-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="fu"&gt;git&lt;/span&gt; submodule init&lt;/span&gt;
24&lt;span id="cb1-4"&gt;&lt;a href="#cb1-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="fu"&gt;git&lt;/span&gt; submodule update&lt;/span&gt;
25&lt;span id="cb1-5"&gt;&lt;a href="#cb1-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
26&lt;span id="cb1-6"&gt;&lt;a href="#cb1-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;# install&lt;/span&gt;&lt;/span&gt;
27&lt;span id="cb1-7"&gt;&lt;a href="#cb1-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="fu"&gt;make&lt;/span&gt; NO_LUA=1&lt;/span&gt;
28&lt;span id="cb1-8"&gt;&lt;a href="#cb1-8" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="fu"&gt;sudo&lt;/span&gt; make install&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
29&lt;p&gt;This would drop the cgit cgi script (and the default css) into &lt;code&gt;/var/www/htdocs/cgit&lt;/code&gt;. You may configure cgit by editing &lt;code&gt;/etc/cgitrc&lt;/code&gt;. I specify the &lt;code&gt;NO_LUA&lt;/code&gt; flag to compile without lua support, exclude that flag if you would like to extend cgit via lua scripts.&lt;/p&gt;
30&lt;h3 id="going-live"&gt;Going live&lt;/h3&gt;
31&lt;p&gt;You might want to use, &lt;a href="https://github.com/gnosek/fcgiwrap"&gt;fcgiwrap&lt;/a&gt;, a &lt;a href="http://www.nongnu.org/fastcgi"&gt;fastcgi&lt;/a&gt; wrapper for &lt;code&gt;cgi&lt;/code&gt; scripts,&lt;/p&gt;
32&lt;div class="sourceCode" id="cb2"&gt;&lt;pre class="sourceCode sh"&gt;&lt;code class="sourceCode bash"&gt;&lt;span id="cb2-1"&gt;&lt;a href="#cb2-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="fu"&gt;sudo&lt;/span&gt; apt install fcgiwrap&lt;/span&gt;
33&lt;span id="cb2-2"&gt;&lt;a href="#cb2-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="fu"&gt;sudo&lt;/span&gt; systemctl start fcgiwrap.socket&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
34&lt;p&gt;Expose the cgit cgi script to the web via &lt;code&gt;nginx&lt;/code&gt;:&lt;/p&gt;
35&lt;pre&gt;&lt;code&gt;# nginx.conf
36server {
37 listen 80;
38 server_name git.example.com;
39
40 # serve static files
41 location ~* ^.+\.(css|png|ico)$ {
42 root /var/www/htdocs/cgit;
43 }
44
45 location / {
46 fastcgi_pass unix:/run/fcgiwrap.socket;
47 fastcgi_param SCRIPT_FILENAME /var/www/htdocs/cgit/cgit.cgi; # the default location of the cgit cgi script
48 fastcgi_param PATH_INFO $uri;
49 fastcgi_param QUERY_STRING $args;
50 }
51}&lt;/code&gt;&lt;/pre&gt;
52&lt;p&gt;Point cgit to your git repositories:&lt;/p&gt;
53&lt;pre&gt;&lt;code&gt;# /etc/cgitrc
54scan-path=/path/to/git/repos&lt;/code&gt;&lt;/pre&gt;
55&lt;p&gt;&lt;strong&gt;&lt;em&gt;Note&lt;/em&gt;&lt;/strong&gt;: &lt;em&gt;&lt;code&gt;scan-path&lt;/code&gt; works best if you stick it at the end of your &lt;code&gt;cgitrc&lt;/code&gt;&lt;/em&gt;.&lt;/p&gt;
56&lt;p&gt;You may now create remote repositories at &lt;code&gt;/path/to/git/repos&lt;/code&gt;, via:&lt;/p&gt;
57&lt;pre&gt;&lt;code&gt;git init --bare&lt;/code&gt;&lt;/pre&gt;
58&lt;p&gt;Add the remote to your local repository:&lt;/p&gt;
59&lt;pre&gt;&lt;code&gt;git remote set-url origin user@remote:/above/path
60git push origin master&lt;/code&gt;&lt;/pre&gt;
61&lt;h3 id="configuration"&gt;Configuration&lt;/h3&gt;
62&lt;p&gt;cgit is fairly easy to configure, all configuration options can be found &lt;a href="https://git.zx2c4.com/cgit/tree/cgitrc.5.txt"&gt;in the manual&lt;/a&gt;, here are a couple of cool ones though:&lt;/p&gt;
63&lt;p&gt;&lt;strong&gt;enable-commit-graph&lt;/strong&gt;: Generates a text based graphical representation of the commit history, similar to &lt;code&gt;git log --graph --oneline&lt;/code&gt;.&lt;/p&gt;
64&lt;pre&gt;&lt;code&gt;| * | Add support for configuration file
65* | | simplify command parsing logic
66* | | Refactor parsers
67* | | Add basic tests
68* | | Merge remote-tracking branch &amp;#39;origin/master&amp;#39; in...
69|\| |
70| * | add installation instructions for nix
71| * | switch to pancurses backendv0.2.2
72| * | bump to v0.2.2
73* | | Merge branch &amp;#39;master&amp;#39; into feature/larger-names...
74|\| |
75| * | enable feature based compilation to support win...
76| * | remove dependency on rustc v1.45, bump to v0.2....
77| * | Merge branch &amp;#39;feature/windows&amp;#39; of https://git...
78| |\ \
79| | * | add windows to github actions
80| | * | switch to crossterm backend
81| | * | Merge branch &amp;#39;fix/duplicate-habits&amp;#39;
82| | |\ \
83| | | * | move duplicate check to command parsing blo...&lt;/code&gt;&lt;/pre&gt;
84&lt;p&gt;&lt;strong&gt;section-from-path&lt;/strong&gt;: This option paired with &lt;code&gt;scan-path&lt;/code&gt; will automatically generate sections in your cgit index page, from the path to each repo. For example, the directory structure used to generate sections on &lt;a href="https://git.peppe.rs"&gt;my cgit instance&lt;/a&gt; looks like this:&lt;/p&gt;
85&lt;pre&gt;&lt;code&gt;├── cli
86│ ├── dijo
87│ ├── eva
88│ ├── pista
89│ ├── taizen
90│ └── xcursorlocate
91├── config
92│ ├── dotfiles
93│ └── nixos
94├── fonts
95│ ├── curie
96│ └── scientifica
97├── languages
98│ └── lisk
99├── libs
100│ ├── cutlass
101│ └── fondant
102├── terminfo
103├── university
104│ └── furby
105└── web
106 └── isostatic&lt;/code&gt;&lt;/pre&gt;
107&lt;h3 id="ease-of-use"&gt;Ease of use&lt;/h3&gt;
108&lt;p&gt;As I mentioned before, &lt;code&gt;cgit&lt;/code&gt; is simply a view into your git repositories, you will have to manually create new repositories by entering your remote and using &lt;code&gt;git init --bare&lt;/code&gt;. Here are a couple of scripts I wrote to perform actions on remotes, think of it as a smaller version of Github’s &lt;code&gt;gh&lt;/code&gt; program.&lt;/p&gt;
109&lt;p&gt;You may save these scripts as &lt;code&gt;git-script-name&lt;/code&gt; and drop them in your &lt;code&gt;$PATH&lt;/code&gt;, and git will automatically add an alias called &lt;code&gt;script-name&lt;/code&gt;, callable via:&lt;/p&gt;
110&lt;pre&gt;&lt;code&gt;git script-name&lt;/code&gt;&lt;/pre&gt;
111&lt;h4 id="git-new-repo"&gt;git-new-repo&lt;/h4&gt;
112&lt;p&gt;Creates a new repository on your remote, the first arg may be a path (section/repo-name) or just the repo name:&lt;/p&gt;
113&lt;pre&gt;&lt;code&gt;#! /usr/bin/env bash
114#
115# usage:
116# git new-repo section/repo-name
117#
118# example:
119# git new-repo fonts/scientifica
120# creates: user@remote:fonts/scientifica
121
122if [ $# -eq 0 ]; then
123 echo &amp;quot;requires an arg&amp;quot;
124 exit 1
125fi
126
127ssh user@remote git init --bare &amp;quot;$1&amp;quot;;&lt;/code&gt;&lt;/pre&gt;
128&lt;h4 id="git-set-desc"&gt;git-set-desc&lt;/h4&gt;
129&lt;p&gt;To set a one line repository description. It simply copies the local &lt;code&gt;.git/description&lt;/code&gt;, into &lt;code&gt;remote/description&lt;/code&gt;. &lt;code&gt;cgit&lt;/code&gt; displays the contents of this file on the index page:&lt;/p&gt;
130&lt;pre&gt;&lt;code&gt;#! /usr/bin/env bash
131#
132# usage:
133# enter repo description into .git/description and run:
134# git set-desc
135
136remote=$(git remote get-url --push origin)
137scp .git/description &amp;quot;$remote/description&amp;quot;&lt;/code&gt;&lt;/pre&gt;</description>
138<link>https://peppe.rs/posts/self-hosting_git/</link>
139<pubDate>Sat, 17 Oct 2020 07:04:00 +0000</pubDate>
140<guid>https://peppe.rs/posts/self-hosting_git/</guid>
141</item>
142<item>
15<title>NixOS</title> 143<title>NixOS</title>
16<description>&lt;p&gt;I have been eyeing operating systems with functional package managers for a while now, aka, NixOS or Guix. Reproducible builds, declarative and rollback-able system configuration, system consistency, all sound pretty cool. I have been using NixOS for about a month now.&lt;/p&gt; 144<description>&lt;p&gt;I have been eyeing operating systems with functional package managers for a while now, aka, NixOS or Guix. Reproducible builds, declarative and rollback-able system configuration, system consistency, all sound pretty cool. I have been using NixOS for about a month now.&lt;/p&gt;
17&lt;h3 id="installation"&gt;Installation&lt;/h3&gt; 145&lt;h3 id="installation"&gt;Installation&lt;/h3&gt;
@@ -29,10 +157,10 @@
29&lt;p&gt;Builds may be generated by specifying a &lt;code&gt;default.nix&lt;/code&gt; file, and running &lt;code&gt;nix-build&lt;/code&gt;. Conventional package managers require you to specify a dependency list, but there is no guarantee that this list is complete. The package will build on your machine even if you forget a dependency. However, with Nix, packages are installed to &lt;code&gt;/nix/store&lt;/code&gt;, and not global paths such as &lt;code&gt;/usr/bin/...&lt;/code&gt;, if your project builds, it means you have included every last one.&lt;/p&gt; 157&lt;p&gt;Builds may be generated by specifying a &lt;code&gt;default.nix&lt;/code&gt; file, and running &lt;code&gt;nix-build&lt;/code&gt;. Conventional package managers require you to specify a dependency list, but there is no guarantee that this list is complete. The package will build on your machine even if you forget a dependency. However, with Nix, packages are installed to &lt;code&gt;/nix/store&lt;/code&gt;, and not global paths such as &lt;code&gt;/usr/bin/...&lt;/code&gt;, if your project builds, it means you have included every last one.&lt;/p&gt;
30&lt;p&gt;Issues on most my projects have been “unable to build because &lt;code&gt;libxcb&lt;/code&gt; is missing”, or “this version of &lt;code&gt;openssl&lt;/code&gt; is too old”. Tools like &lt;code&gt;cargo&lt;/code&gt; and &lt;code&gt;pip&lt;/code&gt; are poor package managers. While they &lt;em&gt;can&lt;/em&gt; guarantee that Rust or Python dependencies are met, they make assumptions about the target system.&lt;/p&gt; 158&lt;p&gt;Issues on most my projects have been “unable to build because &lt;code&gt;libxcb&lt;/code&gt; is missing”, or “this version of &lt;code&gt;openssl&lt;/code&gt; is too old”. Tools like &lt;code&gt;cargo&lt;/code&gt; and &lt;code&gt;pip&lt;/code&gt; are poor package managers. While they &lt;em&gt;can&lt;/em&gt; guarantee that Rust or Python dependencies are met, they make assumptions about the target system.&lt;/p&gt;
31&lt;p&gt;For example, &lt;a href="https://github.com/nerdypepper/site"&gt;this website&lt;/a&gt; is now built using Nix, anyone using Nix may simply, clone the repository and run &lt;code&gt;./generate.sh&lt;/code&gt;, and it would &lt;em&gt;just work&lt;/em&gt;, while keeping your global namespace clean™:&lt;/p&gt; 159&lt;p&gt;For example, &lt;a href="https://github.com/nerdypepper/site"&gt;this website&lt;/a&gt; is now built using Nix, anyone using Nix may simply, clone the repository and run &lt;code&gt;./generate.sh&lt;/code&gt;, and it would &lt;em&gt;just work&lt;/em&gt;, while keeping your global namespace clean™:&lt;/p&gt;
32&lt;div class="sourceCode" id="cb2"&gt;&lt;pre class="sourceCode bash"&gt;&lt;code class="sourceCode bash"&gt;&lt;span id="cb2-1"&gt;&lt;a href="#cb2-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;#! /usr/bin/env nix-shell&lt;/span&gt;&lt;/span&gt; 160&lt;div class="sourceCode" id="cb2"&gt;&lt;pre class="sourceCode bash"&gt;&lt;code class="sourceCode bash"&gt;&lt;span id="cb2-1"&gt;&lt;a href="#cb2-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;#! /usr/bin/env nix-shell&lt;/span&gt;&lt;/span&gt;
33&lt;span id="cb2-2"&gt;&lt;a href="#cb2-2"&gt;&lt;/a&gt;&lt;span class="co"&gt;#! nix-shell -i bash -p eva pandoc esh&lt;/span&gt;&lt;/span&gt; 161&lt;span id="cb2-2"&gt;&lt;a href="#cb2-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;#! nix-shell -i bash -p eva pandoc esh&lt;/span&gt;&lt;/span&gt;
34&lt;span id="cb2-3"&gt;&lt;a href="#cb2-3"&gt;&lt;/a&gt;&lt;/span&gt; 162&lt;span id="cb2-3"&gt;&lt;a href="#cb2-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
35&lt;span id="cb2-4"&gt;&lt;a href="#cb2-4"&gt;&lt;/a&gt;&lt;span class="co"&gt;# some bash magic ;)&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 163&lt;span id="cb2-4"&gt;&lt;a href="#cb2-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;# some bash magic ;)&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
36&lt;p&gt;Dependencies are included with the &lt;code&gt;-p&lt;/code&gt; flag, the shell script is executed with an interpreter, specified with the &lt;code&gt;-i&lt;/code&gt; flag.&lt;/p&gt; 164&lt;p&gt;Dependencies are included with the &lt;code&gt;-p&lt;/code&gt; flag, the shell script is executed with an interpreter, specified with the &lt;code&gt;-i&lt;/code&gt; flag.&lt;/p&gt;
37&lt;h3 id="impressions"&gt;Impressions&lt;/h3&gt; 165&lt;h3 id="impressions"&gt;Impressions&lt;/h3&gt;
38&lt;p&gt;NixOS is by no means, simple. As a newcomer, using Nix was not easy, heck, I had to learn a purely functional, lazy language to just build programs. There is a lot to be desired on the tooling front as well. A well fleshed out LSP plugin would be nice (&lt;a href="https://github.com/nix-community/rnix-lsp"&gt;rnix-lsp looks promising&lt;/a&gt;).&lt;/p&gt; 166&lt;p&gt;NixOS is by no means, simple. As a newcomer, using Nix was not easy, heck, I had to learn a purely functional, lazy language to just build programs. There is a lot to be desired on the tooling front as well. A well fleshed out LSP plugin would be nice (&lt;a href="https://github.com/nix-community/rnix-lsp"&gt;rnix-lsp looks promising&lt;/a&gt;).&lt;/p&gt;
@@ -57,101 +185,101 @@
57&lt;h3 id="lack-of-sum-types"&gt;Lack of Sum types&lt;/h3&gt; 185&lt;h3 id="lack-of-sum-types"&gt;Lack of Sum types&lt;/h3&gt;
58&lt;p&gt;A “Sum” type is a data type that can hold one of many states at a given time, similar to how a boolean can hold a true or a false, not too different from an &lt;code&gt;enum&lt;/code&gt; type in C. Go lacks &lt;code&gt;enum&lt;/code&gt; types unfortunately, and you are forced to resort to crafting your own substitute.&lt;/p&gt; 186&lt;p&gt;A “Sum” type is a data type that can hold one of many states at a given time, similar to how a boolean can hold a true or a false, not too different from an &lt;code&gt;enum&lt;/code&gt; type in C. Go lacks &lt;code&gt;enum&lt;/code&gt; types unfortunately, and you are forced to resort to crafting your own substitute.&lt;/p&gt;
59&lt;p&gt;A type to represent gender for example:&lt;/p&gt; 187&lt;p&gt;A type to represent gender for example:&lt;/p&gt;
60&lt;div class="sourceCode" id="cb1"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb1-1"&gt;&lt;a href="#cb1-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; Gender &lt;span class="dt"&gt;int&lt;/span&gt;&lt;/span&gt; 188&lt;div class="sourceCode" id="cb1"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb1-1"&gt;&lt;a href="#cb1-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; Gender &lt;span class="dt"&gt;int&lt;/span&gt;&lt;/span&gt;
61&lt;span id="cb1-2"&gt;&lt;a href="#cb1-2"&gt;&lt;/a&gt;&lt;/span&gt; 189&lt;span id="cb1-2"&gt;&lt;a href="#cb1-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
62&lt;span id="cb1-3"&gt;&lt;a href="#cb1-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;const&lt;/span&gt; (&lt;/span&gt; 190&lt;span id="cb1-3"&gt;&lt;a href="#cb1-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;const&lt;/span&gt; (&lt;/span&gt;
63&lt;span id="cb1-4"&gt;&lt;a href="#cb1-4"&gt;&lt;/a&gt; Male Gender = &lt;span class="ot"&gt;iota&lt;/span&gt; &lt;span class="co"&gt;// assigns Male to 0&lt;/span&gt;&lt;/span&gt; 191&lt;span id="cb1-4"&gt;&lt;a href="#cb1-4" aria-hidden="true"&gt;&lt;/a&gt; Male Gender = &lt;span class="ot"&gt;iota&lt;/span&gt; &lt;span class="co"&gt;// assigns Male to 0&lt;/span&gt;&lt;/span&gt;
64&lt;span id="cb1-5"&gt;&lt;a href="#cb1-5"&gt;&lt;/a&gt; Female &lt;span class="co"&gt;// assigns Female to 1&lt;/span&gt;&lt;/span&gt; 192&lt;span id="cb1-5"&gt;&lt;a href="#cb1-5" aria-hidden="true"&gt;&lt;/a&gt; Female &lt;span class="co"&gt;// assigns Female to 1&lt;/span&gt;&lt;/span&gt;
65&lt;span id="cb1-6"&gt;&lt;a href="#cb1-6"&gt;&lt;/a&gt; Other &lt;span class="co"&gt;// assigns Other to 2&lt;/span&gt;&lt;/span&gt; 193&lt;span id="cb1-6"&gt;&lt;a href="#cb1-6" aria-hidden="true"&gt;&lt;/a&gt; Other &lt;span class="co"&gt;// assigns Other to 2&lt;/span&gt;&lt;/span&gt;
66&lt;span id="cb1-7"&gt;&lt;a href="#cb1-7"&gt;&lt;/a&gt;)&lt;/span&gt; 194&lt;span id="cb1-7"&gt;&lt;a href="#cb1-7" aria-hidden="true"&gt;&lt;/a&gt;)&lt;/span&gt;
67&lt;span id="cb1-8"&gt;&lt;a href="#cb1-8"&gt;&lt;/a&gt;&lt;/span&gt; 195&lt;span id="cb1-8"&gt;&lt;a href="#cb1-8" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
68&lt;span id="cb1-9"&gt;&lt;a href="#cb1-9"&gt;&lt;/a&gt;fmt.Println(&lt;span class="st"&gt;&amp;quot;My gender is &amp;quot;&lt;/span&gt;, Male)&lt;/span&gt; 196&lt;span id="cb1-9"&gt;&lt;a href="#cb1-9" aria-hidden="true"&gt;&lt;/a&gt;fmt.Println(&lt;span class="st"&gt;&amp;quot;My gender is &amp;quot;&lt;/span&gt;, Male)&lt;/span&gt;
69&lt;span id="cb1-10"&gt;&lt;a href="#cb1-10"&gt;&lt;/a&gt;&lt;span class="co"&gt;// My gender is 0&lt;/span&gt;&lt;/span&gt; 197&lt;span id="cb1-10"&gt;&lt;a href="#cb1-10" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// My gender is 0&lt;/span&gt;&lt;/span&gt;
70&lt;span id="cb1-11"&gt;&lt;a href="#cb1-11"&gt;&lt;/a&gt;&lt;span class="co"&gt;// Oops! We have to implement String() for Gender ...&lt;/span&gt;&lt;/span&gt; 198&lt;span id="cb1-11"&gt;&lt;a href="#cb1-11" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// Oops! We have to implement String() for Gender ...&lt;/span&gt;&lt;/span&gt;
71&lt;span id="cb1-12"&gt;&lt;a href="#cb1-12"&gt;&lt;/a&gt;&lt;/span&gt; 199&lt;span id="cb1-12"&gt;&lt;a href="#cb1-12" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
72&lt;span id="cb1-13"&gt;&lt;a href="#cb1-13"&gt;&lt;/a&gt;&lt;span class="kw"&gt;func&lt;/span&gt; (g Gender) String() &lt;span class="dt"&gt;string&lt;/span&gt; {&lt;/span&gt; 200&lt;span id="cb1-13"&gt;&lt;a href="#cb1-13" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;func&lt;/span&gt; (g Gender) String() &lt;span class="dt"&gt;string&lt;/span&gt; {&lt;/span&gt;
73&lt;span id="cb1-14"&gt;&lt;a href="#cb1-14"&gt;&lt;/a&gt; &lt;span class="kw"&gt;switch&lt;/span&gt; (g) {&lt;/span&gt; 201&lt;span id="cb1-14"&gt;&lt;a href="#cb1-14" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;switch&lt;/span&gt; (g) {&lt;/span&gt;
74&lt;span id="cb1-15"&gt;&lt;a href="#cb1-15"&gt;&lt;/a&gt; &lt;span class="kw"&gt;case&lt;/span&gt; &lt;span class="dv"&gt;0&lt;/span&gt;: &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;Male&amp;quot;&lt;/span&gt;&lt;/span&gt; 202&lt;span id="cb1-15"&gt;&lt;a href="#cb1-15" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;case&lt;/span&gt; &lt;span class="dv"&gt;0&lt;/span&gt;: &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;Male&amp;quot;&lt;/span&gt;&lt;/span&gt;
75&lt;span id="cb1-16"&gt;&lt;a href="#cb1-16"&gt;&lt;/a&gt; &lt;span class="kw"&gt;case&lt;/span&gt; &lt;span class="dv"&gt;1&lt;/span&gt;: &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;Female&amp;quot;&lt;/span&gt;&lt;/span&gt; 203&lt;span id="cb1-16"&gt;&lt;a href="#cb1-16" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;case&lt;/span&gt; &lt;span class="dv"&gt;1&lt;/span&gt;: &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;Female&amp;quot;&lt;/span&gt;&lt;/span&gt;
76&lt;span id="cb1-17"&gt;&lt;a href="#cb1-17"&gt;&lt;/a&gt; &lt;span class="kw"&gt;default&lt;/span&gt;: &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;Other&amp;quot;&lt;/span&gt;&lt;/span&gt; 204&lt;span id="cb1-17"&gt;&lt;a href="#cb1-17" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;default&lt;/span&gt;: &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;Other&amp;quot;&lt;/span&gt;&lt;/span&gt;
77&lt;span id="cb1-18"&gt;&lt;a href="#cb1-18"&gt;&lt;/a&gt; }&lt;/span&gt; 205&lt;span id="cb1-18"&gt;&lt;a href="#cb1-18" aria-hidden="true"&gt;&lt;/a&gt; }&lt;/span&gt;
78&lt;span id="cb1-19"&gt;&lt;a href="#cb1-19"&gt;&lt;/a&gt;}&lt;/span&gt; 206&lt;span id="cb1-19"&gt;&lt;a href="#cb1-19" aria-hidden="true"&gt;&lt;/a&gt;}&lt;/span&gt;
79&lt;span id="cb1-20"&gt;&lt;a href="#cb1-20"&gt;&lt;/a&gt;&lt;/span&gt; 207&lt;span id="cb1-20"&gt;&lt;a href="#cb1-20" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
80&lt;span id="cb1-21"&gt;&lt;a href="#cb1-21"&gt;&lt;/a&gt;&lt;span class="co"&gt;// You can accidentally do stupid stuff like:&lt;/span&gt;&lt;/span&gt; 208&lt;span id="cb1-21"&gt;&lt;a href="#cb1-21" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// You can accidentally do stupid stuff like:&lt;/span&gt;&lt;/span&gt;
81&lt;span id="cb1-22"&gt;&lt;a href="#cb1-22"&gt;&lt;/a&gt;gender := Male + &lt;span class="dv"&gt;1&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 209&lt;span id="cb1-22"&gt;&lt;a href="#cb1-22" aria-hidden="true"&gt;&lt;/a&gt;gender := Male + &lt;span class="dv"&gt;1&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
82&lt;p&gt;The Haskell equivalent of the same:&lt;/p&gt; 210&lt;p&gt;The Haskell equivalent of the same:&lt;/p&gt;
83&lt;div class="sourceCode" id="cb2"&gt;&lt;pre class="sourceCode haskell"&gt;&lt;code class="sourceCode haskell"&gt;&lt;span id="cb2-1"&gt;&lt;a href="#cb2-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;data&lt;/span&gt; &lt;span class="dt"&gt;Gender&lt;/span&gt; &lt;span class="ot"&gt;=&lt;/span&gt; &lt;span class="dt"&gt;Male&lt;/span&gt;&lt;/span&gt; 211&lt;div class="sourceCode" id="cb2"&gt;&lt;pre class="sourceCode haskell"&gt;&lt;code class="sourceCode haskell"&gt;&lt;span id="cb2-1"&gt;&lt;a href="#cb2-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;data&lt;/span&gt; &lt;span class="dt"&gt;Gender&lt;/span&gt; &lt;span class="ot"&gt;=&lt;/span&gt; &lt;span class="dt"&gt;Male&lt;/span&gt;&lt;/span&gt;
84&lt;span id="cb2-2"&gt;&lt;a href="#cb2-2"&gt;&lt;/a&gt; &lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="dt"&gt;Female&lt;/span&gt;&lt;/span&gt; 212&lt;span id="cb2-2"&gt;&lt;a href="#cb2-2" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="dt"&gt;Female&lt;/span&gt;&lt;/span&gt;
85&lt;span id="cb2-3"&gt;&lt;a href="#cb2-3"&gt;&lt;/a&gt; &lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="dt"&gt;Other&lt;/span&gt;&lt;/span&gt; 213&lt;span id="cb2-3"&gt;&lt;a href="#cb2-3" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="dt"&gt;Other&lt;/span&gt;&lt;/span&gt;
86&lt;span id="cb2-4"&gt;&lt;a href="#cb2-4"&gt;&lt;/a&gt; &lt;span class="kw"&gt;deriving&lt;/span&gt; (&lt;span class="dt"&gt;Show&lt;/span&gt;)&lt;/span&gt; 214&lt;span id="cb2-4"&gt;&lt;a href="#cb2-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;deriving&lt;/span&gt; (&lt;span class="dt"&gt;Show&lt;/span&gt;)&lt;/span&gt;
87&lt;span id="cb2-5"&gt;&lt;a href="#cb2-5"&gt;&lt;/a&gt;&lt;/span&gt; 215&lt;span id="cb2-5"&gt;&lt;a href="#cb2-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
88&lt;span id="cb2-6"&gt;&lt;a href="#cb2-6"&gt;&lt;/a&gt;&lt;span class="fu"&gt;print&lt;/span&gt; &lt;span class="op"&gt;$&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;My gender is &amp;quot;&lt;/span&gt; &lt;span class="op"&gt;++&lt;/span&gt; (&lt;span class="fu"&gt;show&lt;/span&gt; &lt;span class="dt"&gt;Male&lt;/span&gt;)&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 216&lt;span id="cb2-6"&gt;&lt;a href="#cb2-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="fu"&gt;print&lt;/span&gt; &lt;span class="op"&gt;$&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;My gender is &amp;quot;&lt;/span&gt; &lt;span class="op"&gt;++&lt;/span&gt; (&lt;span class="fu"&gt;show&lt;/span&gt; &lt;span class="dt"&gt;Male&lt;/span&gt;)&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
89&lt;h3 id="type-assertions"&gt;Type Assertions&lt;/h3&gt; 217&lt;h3 id="type-assertions"&gt;Type Assertions&lt;/h3&gt;
90&lt;p&gt;A downcast with an optional error check? What could go wrong?&lt;/p&gt; 218&lt;p&gt;A downcast with an optional error check? What could go wrong?&lt;/p&gt;
91&lt;p&gt;Type assertions in Go allow you to do:&lt;/p&gt; 219&lt;p&gt;Type assertions in Go allow you to do:&lt;/p&gt;
92&lt;div class="sourceCode" id="cb3"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb3-1"&gt;&lt;a href="#cb3-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;var&lt;/span&gt; x &lt;span class="kw"&gt;interface&lt;/span&gt;{} = &lt;span class="dv"&gt;7&lt;/span&gt;&lt;/span&gt; 220&lt;div class="sourceCode" id="cb3"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb3-1"&gt;&lt;a href="#cb3-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;var&lt;/span&gt; x &lt;span class="kw"&gt;interface&lt;/span&gt;{} = &lt;span class="dv"&gt;7&lt;/span&gt;&lt;/span&gt;
93&lt;span id="cb3-2"&gt;&lt;a href="#cb3-2"&gt;&lt;/a&gt;y, goodToGo := x.(&lt;span class="dt"&gt;int&lt;/span&gt;)&lt;/span&gt; 221&lt;span id="cb3-2"&gt;&lt;a href="#cb3-2" aria-hidden="true"&gt;&lt;/a&gt;y, goodToGo := x.(&lt;span class="dt"&gt;int&lt;/span&gt;)&lt;/span&gt;
94&lt;span id="cb3-3"&gt;&lt;a href="#cb3-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;if&lt;/span&gt; goodToGo {&lt;/span&gt; 222&lt;span id="cb3-3"&gt;&lt;a href="#cb3-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;if&lt;/span&gt; goodToGo {&lt;/span&gt;
95&lt;span id="cb3-4"&gt;&lt;a href="#cb3-4"&gt;&lt;/a&gt; fmt.Println(y)&lt;/span&gt; 223&lt;span id="cb3-4"&gt;&lt;a href="#cb3-4" aria-hidden="true"&gt;&lt;/a&gt; fmt.Println(y)&lt;/span&gt;
96&lt;span id="cb3-5"&gt;&lt;a href="#cb3-5"&gt;&lt;/a&gt;}&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 224&lt;span id="cb3-5"&gt;&lt;a href="#cb3-5" aria-hidden="true"&gt;&lt;/a&gt;}&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
97&lt;p&gt;The error check however is optional:&lt;/p&gt; 225&lt;p&gt;The error check however is optional:&lt;/p&gt;
98&lt;div class="sourceCode" id="cb4"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb4-1"&gt;&lt;a href="#cb4-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;var&lt;/span&gt; x &lt;span class="kw"&gt;interface&lt;/span&gt;{} = &lt;span class="dv"&gt;7&lt;/span&gt;&lt;/span&gt; 226&lt;div class="sourceCode" id="cb4"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb4-1"&gt;&lt;a href="#cb4-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;var&lt;/span&gt; x &lt;span class="kw"&gt;interface&lt;/span&gt;{} = &lt;span class="dv"&gt;7&lt;/span&gt;&lt;/span&gt;
99&lt;span id="cb4-2"&gt;&lt;a href="#cb4-2"&gt;&lt;/a&gt;&lt;span class="kw"&gt;var&lt;/span&gt; y := x.(&lt;span class="dt"&gt;float64&lt;/span&gt;)&lt;/span&gt; 227&lt;span id="cb4-2"&gt;&lt;a href="#cb4-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;var&lt;/span&gt; y := x.(&lt;span class="dt"&gt;float64&lt;/span&gt;)&lt;/span&gt;
100&lt;span id="cb4-3"&gt;&lt;a href="#cb4-3"&gt;&lt;/a&gt;fmt.Println(y)&lt;/span&gt; 228&lt;span id="cb4-3"&gt;&lt;a href="#cb4-3" aria-hidden="true"&gt;&lt;/a&gt;fmt.Println(y)&lt;/span&gt;
101&lt;span id="cb4-4"&gt;&lt;a href="#cb4-4"&gt;&lt;/a&gt;&lt;span class="co"&gt;// results in a runtime error:&lt;/span&gt;&lt;/span&gt; 229&lt;span id="cb4-4"&gt;&lt;a href="#cb4-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// results in a runtime error:&lt;/span&gt;&lt;/span&gt;
102&lt;span id="cb4-5"&gt;&lt;a href="#cb4-5"&gt;&lt;/a&gt;&lt;span class="co"&gt;// panic: interface conversion: interface {} is int, not float64&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 230&lt;span id="cb4-5"&gt;&lt;a href="#cb4-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// panic: interface conversion: interface {} is int, not float64&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
103&lt;h3 id="date-and-time"&gt;Date and Time&lt;/h3&gt; 231&lt;h3 id="date-and-time"&gt;Date and Time&lt;/h3&gt;
104&lt;p&gt;Anyone that has written Go previously, will probably already know what I am getting at here. For the uninitiated, parsing and formatting dates in Go requires a “layout”. This “layout” is based on magical reference date:&lt;/p&gt; 232&lt;p&gt;Anyone that has written Go previously, will probably already know what I am getting at here. For the uninitiated, parsing and formatting dates in Go requires a “layout”. This “layout” is based on magical reference date:&lt;/p&gt;
105&lt;pre&gt;&lt;code&gt;Mon Jan 2 15:04:05 MST 2006&lt;/code&gt;&lt;/pre&gt; 233&lt;pre&gt;&lt;code&gt;Mon Jan 2 15:04:05 MST 2006&lt;/code&gt;&lt;/pre&gt;
106&lt;p&gt;Which is the date produced when you write the first seven natural numbers like so:&lt;/p&gt; 234&lt;p&gt;Which is the date produced when you write the first seven natural numbers like so:&lt;/p&gt;
107&lt;pre&gt;&lt;code&gt;01/02 03:04:05 &amp;#39;06 -0700&lt;/code&gt;&lt;/pre&gt; 235&lt;pre&gt;&lt;code&gt;01/02 03:04:05 &amp;#39;06 -0700&lt;/code&gt;&lt;/pre&gt;
108&lt;p&gt;Parsing a string in &lt;code&gt;YYYY-MM-DD&lt;/code&gt; format would look something like:&lt;/p&gt; 236&lt;p&gt;Parsing a string in &lt;code&gt;YYYY-MM-DD&lt;/code&gt; format would look something like:&lt;/p&gt;
109&lt;div class="sourceCode" id="cb7"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb7-1"&gt;&lt;a href="#cb7-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;const&lt;/span&gt; layout = &lt;span class="st"&gt;&amp;quot;2006-01-02&amp;quot;&lt;/span&gt;&lt;/span&gt; 237&lt;div class="sourceCode" id="cb7"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb7-1"&gt;&lt;a href="#cb7-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;const&lt;/span&gt; layout = &lt;span class="st"&gt;&amp;quot;2006-01-02&amp;quot;&lt;/span&gt;&lt;/span&gt;
110&lt;span id="cb7-2"&gt;&lt;a href="#cb7-2"&gt;&lt;/a&gt;time.Parse(layout, &lt;span class="st"&gt;&amp;quot;2020-08-01&amp;quot;&lt;/span&gt;)&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 238&lt;span id="cb7-2"&gt;&lt;a href="#cb7-2" aria-hidden="true"&gt;&lt;/a&gt;time.Parse(layout, &lt;span class="st"&gt;&amp;quot;2020-08-01&amp;quot;&lt;/span&gt;)&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
111&lt;p&gt;This so-called “intuitive” method of formatting dates doesn’t allow you to print &lt;code&gt;0000 hrs&lt;/code&gt; as &lt;code&gt;2400 hrs&lt;/code&gt;, it doesn’t allow you to omit the leading zero in 24 hour formats. It is rife with inconveniences, if only there were a &lt;a href="https://man7.org/linux/man-pages/man3/strftime.3.html"&gt;tried and tested&lt;/a&gt; date formatting convention …&lt;/p&gt; 239&lt;p&gt;This so-called “intuitive” method of formatting dates doesn’t allow you to print &lt;code&gt;0000 hrs&lt;/code&gt; as &lt;code&gt;2400 hrs&lt;/code&gt;, it doesn’t allow you to omit the leading zero in 24 hour formats. It is rife with inconveniences, if only there were a &lt;a href="https://man7.org/linux/man-pages/man3/strftime.3.html"&gt;tried and tested&lt;/a&gt; date formatting convention …&lt;/p&gt;
112&lt;h3 id="statements-over-expressions"&gt;Statements over Expressions&lt;/h3&gt; 240&lt;h3 id="statements-over-expressions"&gt;Statements over Expressions&lt;/h3&gt;
113&lt;p&gt;Statements have side effects, expressions return values. More often than not, expressions are easier to understand at a glance: evaluate the LHS and assign the same to the RHS.&lt;/p&gt; 241&lt;p&gt;Statements have side effects, expressions return values. More often than not, expressions are easier to understand at a glance: evaluate the LHS and assign the same to the RHS.&lt;/p&gt;
114&lt;p&gt;Rust allows you to create local namespaces, and treats blocks (&lt;code&gt;{}&lt;/code&gt;) as expressions:&lt;/p&gt; 242&lt;p&gt;Rust allows you to create local namespaces, and treats blocks (&lt;code&gt;{}&lt;/code&gt;) as expressions:&lt;/p&gt;
115&lt;div class="sourceCode" id="cb8"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb8-1"&gt;&lt;a href="#cb8-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;let&lt;/span&gt; twenty_seven = &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 243&lt;div class="sourceCode" id="cb8"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb8-1"&gt;&lt;a href="#cb8-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;let&lt;/span&gt; twenty_seven &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
116&lt;span id="cb8-2"&gt;&lt;a href="#cb8-2"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; three = &lt;span class="dv"&gt;1&lt;/span&gt; + &lt;span class="dv"&gt;2&lt;/span&gt;;&lt;/span&gt; 244&lt;span id="cb8-2"&gt;&lt;a href="#cb8-2" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; three &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="dv"&gt;1&lt;/span&gt; &lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="dv"&gt;2&lt;/span&gt;&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
117&lt;span id="cb8-3"&gt;&lt;a href="#cb8-3"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; nine = three * three;&lt;/span&gt; 245&lt;span id="cb8-3"&gt;&lt;a href="#cb8-3" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; nine &lt;span class="op"&gt;=&lt;/span&gt; three &lt;span class="op"&gt;*&lt;/span&gt; three&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
118&lt;span id="cb8-4"&gt;&lt;a href="#cb8-4"&gt;&lt;/a&gt; nine * three&lt;/span&gt; 246&lt;span id="cb8-4"&gt;&lt;a href="#cb8-4" aria-hidden="true"&gt;&lt;/a&gt; nine &lt;span class="op"&gt;*&lt;/span&gt; three&lt;/span&gt;
119&lt;span id="cb8-5"&gt;&lt;a href="#cb8-5"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 247&lt;span id="cb8-5"&gt;&lt;a href="#cb8-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;};&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
120&lt;p&gt;The Go equivalent of the same:&lt;/p&gt; 248&lt;p&gt;The Go equivalent of the same:&lt;/p&gt;
121&lt;div class="sourceCode" id="cb9"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb9-1"&gt;&lt;a href="#cb9-1"&gt;&lt;/a&gt;twenty_seven := &lt;span class="ot"&gt;nil&lt;/span&gt;&lt;/span&gt; 249&lt;div class="sourceCode" id="cb9"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb9-1"&gt;&lt;a href="#cb9-1" aria-hidden="true"&gt;&lt;/a&gt;twenty_seven := &lt;span class="ot"&gt;nil&lt;/span&gt;&lt;/span&gt;
122&lt;span id="cb9-2"&gt;&lt;a href="#cb9-2"&gt;&lt;/a&gt;&lt;/span&gt; 250&lt;span id="cb9-2"&gt;&lt;a href="#cb9-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
123&lt;span id="cb9-3"&gt;&lt;a href="#cb9-3"&gt;&lt;/a&gt;three := &lt;span class="dv"&gt;1&lt;/span&gt; + &lt;span class="dv"&gt;2&lt;/span&gt;&lt;/span&gt; 251&lt;span id="cb9-3"&gt;&lt;a href="#cb9-3" aria-hidden="true"&gt;&lt;/a&gt;three := &lt;span class="dv"&gt;1&lt;/span&gt; + &lt;span class="dv"&gt;2&lt;/span&gt;&lt;/span&gt;
124&lt;span id="cb9-4"&gt;&lt;a href="#cb9-4"&gt;&lt;/a&gt;nine := three * three&lt;/span&gt; 252&lt;span id="cb9-4"&gt;&lt;a href="#cb9-4" aria-hidden="true"&gt;&lt;/a&gt;nine := three * three&lt;/span&gt;
125&lt;span id="cb9-5"&gt;&lt;a href="#cb9-5"&gt;&lt;/a&gt;twenty_seven = nine * three&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 253&lt;span id="cb9-5"&gt;&lt;a href="#cb9-5" aria-hidden="true"&gt;&lt;/a&gt;twenty_seven = nine * three&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
126&lt;h3 id="erroring-out-on-unused-variables"&gt;Erroring out on unused variables&lt;/h3&gt; 254&lt;h3 id="erroring-out-on-unused-variables"&gt;Erroring out on unused variables&lt;/h3&gt;
127&lt;p&gt;Want to quickly prototype something? Go says no! In all seriousness, a warning would suffice, I don’t want to have to go back and comment each unused import out, only to come back and uncomment them a few seconds later.&lt;/p&gt; 255&lt;p&gt;Want to quickly prototype something? Go says no! In all seriousness, a warning would suffice, I don’t want to have to go back and comment each unused import out, only to come back and uncomment them a few seconds later.&lt;/p&gt;
128&lt;h3 id="error-handling"&gt;Error handling&lt;/h3&gt; 256&lt;h3 id="error-handling"&gt;Error handling&lt;/h3&gt;
129&lt;div class="sourceCode" id="cb10"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb10-1"&gt;&lt;a href="#cb10-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;if&lt;/span&gt; err != &lt;span class="ot"&gt;nil&lt;/span&gt; { ... }&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 257&lt;div class="sourceCode" id="cb10"&gt;&lt;pre class="sourceCode go"&gt;&lt;code class="sourceCode go"&gt;&lt;span id="cb10-1"&gt;&lt;a href="#cb10-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;if&lt;/span&gt; err != &lt;span class="ot"&gt;nil&lt;/span&gt; { ... }&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
130&lt;p&gt;Need I say more? I will, for good measure:&lt;/p&gt; 258&lt;p&gt;Need I say more? I will, for good measure:&lt;/p&gt;
131&lt;ol type="1"&gt; 259&lt;ol type="1"&gt;
132&lt;li&gt;Error handling is optional&lt;/li&gt; 260&lt;li&gt;Error handling is optional&lt;/li&gt;
133&lt;li&gt;Errors are propagated via a clunky &lt;code&gt;if&lt;/code&gt; + &lt;code&gt;return&lt;/code&gt; statement&lt;/li&gt; 261&lt;li&gt;Errors are propagated via a clunky &lt;code&gt;if&lt;/code&gt; + &lt;code&gt;return&lt;/code&gt; statement&lt;/li&gt;
134&lt;/ol&gt; 262&lt;/ol&gt;
135&lt;p&gt;I prefer Haskell’s “Monadic” error handling, which is employed by Rust as well:&lt;/p&gt; 263&lt;p&gt;I prefer Haskell’s “Monadic” error handling, which is employed by Rust as well:&lt;/p&gt;
136&lt;div class="sourceCode" id="cb11"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb11-1"&gt;&lt;a href="#cb11-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// 1. error handling is compulsory&lt;/span&gt;&lt;/span&gt; 264&lt;div class="sourceCode" id="cb11"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb11-1"&gt;&lt;a href="#cb11-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// 1. error handling is compulsory&lt;/span&gt;&lt;/span&gt;
137&lt;span id="cb11-2"&gt;&lt;a href="#cb11-2"&gt;&lt;/a&gt;&lt;span class="co"&gt;// 2. errors are propagated with the `?` operator&lt;/span&gt;&lt;/span&gt; 265&lt;span id="cb11-2"&gt;&lt;a href="#cb11-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// 2. errors are propagated with the `?` operator&lt;/span&gt;&lt;/span&gt;
138&lt;span id="cb11-3"&gt;&lt;a href="#cb11-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; foo() -&amp;gt; &lt;span class="dt"&gt;Result&lt;/span&gt;&amp;lt;&lt;span class="dt"&gt;String&lt;/span&gt;, &lt;span class="pp"&gt;io::&lt;/span&gt;Error&amp;gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 266&lt;span id="cb11-3"&gt;&lt;a href="#cb11-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; foo() &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;Result&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="dt"&gt;String&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; &lt;span class="pp"&gt;io::&lt;/span&gt;&lt;span class="bu"&gt;Error&lt;/span&gt;&lt;span class="op"&gt;&amp;gt;&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
139&lt;span id="cb11-4"&gt;&lt;a href="#cb11-4"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; &lt;span class="kw"&gt;mut&lt;/span&gt; f = &lt;span class="pp"&gt;File::&lt;/span&gt;open(&lt;span class="st"&gt;&amp;quot;foo.txt&amp;quot;&lt;/span&gt;)?; &lt;span class="co"&gt;// return if error&lt;/span&gt;&lt;/span&gt; 267&lt;span id="cb11-4"&gt;&lt;a href="#cb11-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; &lt;span class="kw"&gt;mut&lt;/span&gt; f &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="pp"&gt;File::&lt;/span&gt;open(&lt;span class="st"&gt;&amp;quot;foo.txt&amp;quot;&lt;/span&gt;)&lt;span class="op"&gt;?;&lt;/span&gt; &lt;span class="co"&gt;// return if error&lt;/span&gt;&lt;/span&gt;
140&lt;span id="cb11-5"&gt;&lt;a href="#cb11-5"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; &lt;span class="kw"&gt;mut&lt;/span&gt; s = &lt;span class="dt"&gt;String&lt;/span&gt;::new();&lt;/span&gt; 268&lt;span id="cb11-5"&gt;&lt;a href="#cb11-5" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; &lt;span class="kw"&gt;mut&lt;/span&gt; s &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="dt"&gt;String&lt;/span&gt;&lt;span class="pp"&gt;::&lt;/span&gt;new()&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
141&lt;span id="cb11-6"&gt;&lt;a href="#cb11-6"&gt;&lt;/a&gt;&lt;/span&gt; 269&lt;span id="cb11-6"&gt;&lt;a href="#cb11-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
142&lt;span id="cb11-7"&gt;&lt;a href="#cb11-7"&gt;&lt;/a&gt; f.read_to_string(&amp;amp;&lt;span class="kw"&gt;mut&lt;/span&gt; s)?; &lt;span class="co"&gt;// return if error&lt;/span&gt;&lt;/span&gt; 270&lt;span id="cb11-7"&gt;&lt;a href="#cb11-7" aria-hidden="true"&gt;&lt;/a&gt; f&lt;span class="op"&gt;.&lt;/span&gt;read_to_string(&lt;span class="op"&gt;&amp;amp;&lt;/span&gt;&lt;span class="kw"&gt;mut&lt;/span&gt; s)&lt;span class="op"&gt;?;&lt;/span&gt; &lt;span class="co"&gt;// return if error&lt;/span&gt;&lt;/span&gt;
143&lt;span id="cb11-8"&gt;&lt;a href="#cb11-8"&gt;&lt;/a&gt;&lt;/span&gt; 271&lt;span id="cb11-8"&gt;&lt;a href="#cb11-8" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
144&lt;span id="cb11-9"&gt;&lt;a href="#cb11-9"&gt;&lt;/a&gt; &lt;span class="cn"&gt;Ok&lt;/span&gt;(s) &lt;span class="co"&gt;// all good, return a string inside a `Result` context&lt;/span&gt;&lt;/span&gt; 272&lt;span id="cb11-9"&gt;&lt;a href="#cb11-9" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="cn"&gt;Ok&lt;/span&gt;(s) &lt;span class="co"&gt;// all good, return a string inside a `Result` context&lt;/span&gt;&lt;/span&gt;
145&lt;span id="cb11-10"&gt;&lt;a href="#cb11-10"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 273&lt;span id="cb11-10"&gt;&lt;a href="#cb11-10" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
146&lt;span id="cb11-11"&gt;&lt;a href="#cb11-11"&gt;&lt;/a&gt;&lt;/span&gt; 274&lt;span id="cb11-11"&gt;&lt;a href="#cb11-11" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
147&lt;span id="cb11-12"&gt;&lt;a href="#cb11-12"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; main() &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 275&lt;span id="cb11-12"&gt;&lt;a href="#cb11-12" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; main() &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
148&lt;span id="cb11-13"&gt;&lt;a href="#cb11-13"&gt;&lt;/a&gt; &lt;span class="co"&gt;// `contents` is an enum known as Result:&lt;/span&gt;&lt;/span&gt; 276&lt;span id="cb11-13"&gt;&lt;a href="#cb11-13" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="co"&gt;// `contents` is an enum known as Result:&lt;/span&gt;&lt;/span&gt;
149&lt;span id="cb11-14"&gt;&lt;a href="#cb11-14"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; contents = foo();&lt;/span&gt; 277&lt;span id="cb11-14"&gt;&lt;a href="#cb11-14" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; contents &lt;span class="op"&gt;=&lt;/span&gt; foo()&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
150&lt;span id="cb11-15"&gt;&lt;a href="#cb11-15"&gt;&lt;/a&gt; &lt;span class="kw"&gt;match&lt;/span&gt; contents &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 278&lt;span id="cb11-15"&gt;&lt;a href="#cb11-15" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;match&lt;/span&gt; contents &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
151&lt;span id="cb11-16"&gt;&lt;a href="#cb11-16"&gt;&lt;/a&gt; &lt;span class="cn"&gt;Ok&lt;/span&gt;(c) =&amp;gt; &lt;span class="pp"&gt;println!&lt;/span&gt;(c),&lt;/span&gt; 279&lt;span id="cb11-16"&gt;&lt;a href="#cb11-16" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="cn"&gt;Ok&lt;/span&gt;(c) &lt;span class="op"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="pp"&gt;println!&lt;/span&gt;(c)&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
152&lt;span id="cb11-17"&gt;&lt;a href="#cb11-17"&gt;&lt;/a&gt; &lt;span class="cn"&gt;Err&lt;/span&gt;(e) =&amp;gt; &lt;span class="pp"&gt;eprintln!&lt;/span&gt;(e)&lt;/span&gt; 280&lt;span id="cb11-17"&gt;&lt;a href="#cb11-17" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="cn"&gt;Err&lt;/span&gt;(e) &lt;span class="op"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="pp"&gt;eprintln!&lt;/span&gt;(e)&lt;/span&gt;
153&lt;span id="cb11-18"&gt;&lt;a href="#cb11-18"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 281&lt;span id="cb11-18"&gt;&lt;a href="#cb11-18" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
154&lt;span id="cb11-19"&gt;&lt;a href="#cb11-19"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 282&lt;span id="cb11-19"&gt;&lt;a href="#cb11-19" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
155&lt;h3 id="conclusion"&gt;Conclusion&lt;/h3&gt; 283&lt;h3 id="conclusion"&gt;Conclusion&lt;/h3&gt;
156&lt;p&gt;I did not want to conclude without talking about stylistic choices, lack of metaprogramming, bizzare export rules, but, I am too busy converting my &lt;code&gt;interface{}&lt;/code&gt; types into actual generic code for Go v2.&lt;/p&gt;</description> 284&lt;p&gt;I did not want to conclude without talking about stylistic choices, lack of metaprogramming, bizzare export rules, but, I am too busy converting my &lt;code&gt;interface{}&lt;/code&gt; types into actual generic code for Go v2.&lt;/p&gt;</description>
157<link>https://peppe.rs/posts/gripes_with_go/</link> 285<link>https://peppe.rs/posts/gripes_with_go/</link>
@@ -231,17 +359,17 @@ h(x)(y)(z) = g(y)(z) = k(z) = v&lt;/code&gt;&lt;/pre&gt;
231&lt;p&gt;We will be using Attribute macros to convert a Rust function into a curried Rust function, which we should be able to call via: &lt;code&gt;function(arg1)(arg2)&lt;/code&gt;.&lt;/p&gt; 359&lt;p&gt;We will be using Attribute macros to convert a Rust function into a curried Rust function, which we should be able to call via: &lt;code&gt;function(arg1)(arg2)&lt;/code&gt;.&lt;/p&gt;
232&lt;h3 id="definitions"&gt;Definitions&lt;/h3&gt; 360&lt;h3 id="definitions"&gt;Definitions&lt;/h3&gt;
233&lt;p&gt;Being respectable programmers, we define the input to and the output from our proc-macro. Here’s a good non-trivial function to start out with:&lt;/p&gt; 361&lt;p&gt;Being respectable programmers, we define the input to and the output from our proc-macro. Here’s a good non-trivial function to start out with:&lt;/p&gt;
234&lt;div class="sourceCode" id="cb4"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb4-1"&gt;&lt;a href="#cb4-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x: &lt;span class="dt"&gt;u32&lt;/span&gt;, y: &lt;span class="dt"&gt;u32&lt;/span&gt;, z: &lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 362&lt;div class="sourceCode" id="cb4"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb4-1"&gt;&lt;a href="#cb4-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; y&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; z&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
235&lt;span id="cb4-2"&gt;&lt;a href="#cb4-2"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; x + y + z;&lt;/span&gt; 363&lt;span id="cb4-2"&gt;&lt;a href="#cb4-2" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; x &lt;span class="op"&gt;+&lt;/span&gt; y &lt;span class="op"&gt;+&lt;/span&gt; z&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
236&lt;span id="cb4-3"&gt;&lt;a href="#cb4-3"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 364&lt;span id="cb4-3"&gt;&lt;a href="#cb4-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
237&lt;p&gt;Hmm, what would our output look like? What should our proc-macro generate ideally? Well, if we understood currying correctly, we should accept an argument and return a function that accepts an argument and returns … you get the point. Something like this should do:&lt;/p&gt; 365&lt;p&gt;Hmm, what would our output look like? What should our proc-macro generate ideally? Well, if we understood currying correctly, we should accept an argument and return a function that accepts an argument and returns … you get the point. Something like this should do:&lt;/p&gt;
238&lt;div class="sourceCode" id="cb5"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb5-1"&gt;&lt;a href="#cb5-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add_curried1(x: &lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; ? &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 366&lt;div class="sourceCode" id="cb5"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb5-1"&gt;&lt;a href="#cb5-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add_curried1(x&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="op"&gt;?&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
239&lt;span id="cb5-2"&gt;&lt;a href="#cb5-2"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; add_curried2 (y: &lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; ? &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 367&lt;span id="cb5-2"&gt;&lt;a href="#cb5-2" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; add_curried2 (y&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="op"&gt;?&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
240&lt;span id="cb5-3"&gt;&lt;a href="#cb5-3"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; add_curried3 (z: &lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 368&lt;span id="cb5-3"&gt;&lt;a href="#cb5-3" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; add_curried3 (z&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
241&lt;span id="cb5-4"&gt;&lt;a href="#cb5-4"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; x + y + z;&lt;/span&gt; 369&lt;span id="cb5-4"&gt;&lt;a href="#cb5-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; x &lt;span class="op"&gt;+&lt;/span&gt; y &lt;span class="op"&gt;+&lt;/span&gt; z&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
242&lt;span id="cb5-5"&gt;&lt;a href="#cb5-5"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 370&lt;span id="cb5-5"&gt;&lt;a href="#cb5-5" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
243&lt;span id="cb5-6"&gt;&lt;a href="#cb5-6"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 371&lt;span id="cb5-6"&gt;&lt;a href="#cb5-6" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
244&lt;span id="cb5-7"&gt;&lt;a href="#cb5-7"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 372&lt;span id="cb5-7"&gt;&lt;a href="#cb5-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
245&lt;p&gt;A couple of things to note:&lt;/p&gt; 373&lt;p&gt;A couple of things to note:&lt;/p&gt;
246&lt;p&gt;&lt;strong&gt;Return types&lt;/strong&gt;&lt;br /&gt; 374&lt;p&gt;&lt;strong&gt;Return types&lt;/strong&gt;&lt;br /&gt;
247We have placed &lt;code&gt;?&lt;/code&gt;s in place of return types. Let’s try to fix that. &lt;code&gt;add_curried3&lt;/code&gt; returns the ‘value’, so &lt;code&gt;u32&lt;/code&gt; is accurate. &lt;code&gt;add_curried2&lt;/code&gt; returns &lt;code&gt;add_curried3&lt;/code&gt;. What is the type of &lt;code&gt;add_curried3&lt;/code&gt;? It is a function that takes in a &lt;code&gt;u32&lt;/code&gt; and returns a &lt;code&gt;u32&lt;/code&gt;. So a &lt;code&gt;fn(u32) -&amp;gt; u32&lt;/code&gt; will do right? No, I’ll explain why in the next point, but for now, we will make use of the &lt;code&gt;Fn&lt;/code&gt; trait, our return type is &lt;code&gt;impl Fn(u32) -&amp;gt; u32&lt;/code&gt;. This basically tells the compiler that we will be returning something function-like, a.k.a, behaves like a &lt;code&gt;Fn&lt;/code&gt;. Cool!&lt;/p&gt; 375We have placed &lt;code&gt;?&lt;/code&gt;s in place of return types. Let’s try to fix that. &lt;code&gt;add_curried3&lt;/code&gt; returns the ‘value’, so &lt;code&gt;u32&lt;/code&gt; is accurate. &lt;code&gt;add_curried2&lt;/code&gt; returns &lt;code&gt;add_curried3&lt;/code&gt;. What is the type of &lt;code&gt;add_curried3&lt;/code&gt;? It is a function that takes in a &lt;code&gt;u32&lt;/code&gt; and returns a &lt;code&gt;u32&lt;/code&gt;. So a &lt;code&gt;fn(u32) -&amp;gt; u32&lt;/code&gt; will do right? No, I’ll explain why in the next point, but for now, we will make use of the &lt;code&gt;Fn&lt;/code&gt; trait, our return type is &lt;code&gt;impl Fn(u32) -&amp;gt; u32&lt;/code&gt;. This basically tells the compiler that we will be returning something function-like, a.k.a, behaves like a &lt;code&gt;Fn&lt;/code&gt;. Cool!&lt;/p&gt;
@@ -254,9 +382,9 @@ We have placed &lt;code&gt;?&lt;/code&gt;s in place of return types. Let’s try
254A function cannot access it’s environment. Our solution will not work. &lt;code&gt;add_curried3&lt;/code&gt; attempts to access &lt;code&gt;x&lt;/code&gt;, which is not allowed! A closure&lt;a href="#fn1" class="footnote-ref" id="fnref1" role="doc-noteref"&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;/a&gt; however, can. If we are returning a closure, our return type must be &lt;code&gt;impl Fn&lt;/code&gt;, and not &lt;code&gt;fn&lt;/code&gt;. The difference between the &lt;code&gt;Fn&lt;/code&gt; trait and function pointers is beyond the scope of this post.&lt;/p&gt; 382A function cannot access it’s environment. Our solution will not work. &lt;code&gt;add_curried3&lt;/code&gt; attempts to access &lt;code&gt;x&lt;/code&gt;, which is not allowed! A closure&lt;a href="#fn1" class="footnote-ref" id="fnref1" role="doc-noteref"&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;/a&gt; however, can. If we are returning a closure, our return type must be &lt;code&gt;impl Fn&lt;/code&gt;, and not &lt;code&gt;fn&lt;/code&gt;. The difference between the &lt;code&gt;Fn&lt;/code&gt; trait and function pointers is beyond the scope of this post.&lt;/p&gt;
255&lt;h3 id="refinement"&gt;Refinement&lt;/h3&gt; 383&lt;h3 id="refinement"&gt;Refinement&lt;/h3&gt;
256&lt;p&gt;Armed with knowledge, we refine our expected output, this time, employing closures:&lt;/p&gt; 384&lt;p&gt;Armed with knowledge, we refine our expected output, this time, employing closures:&lt;/p&gt;
257&lt;div class="sourceCode" id="cb8"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb8-1"&gt;&lt;a href="#cb8-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x: &lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 385&lt;div class="sourceCode" id="cb8"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb8-1"&gt;&lt;a href="#cb8-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
258&lt;span id="cb8-2"&gt;&lt;a href="#cb8-2"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; |y| &lt;span class="kw"&gt;move&lt;/span&gt; |z| x + y + z;&lt;/span&gt; 386&lt;span id="cb8-2"&gt;&lt;a href="#cb8-2" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;y&lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;z&lt;span class="op"&gt;|&lt;/span&gt; x &lt;span class="op"&gt;+&lt;/span&gt; y &lt;span class="op"&gt;+&lt;/span&gt; z&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
259&lt;span id="cb8-3"&gt;&lt;a href="#cb8-3"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 387&lt;span id="cb8-3"&gt;&lt;a href="#cb8-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
260&lt;p&gt;Alas, that does not compile either! It errors out with the following message:&lt;/p&gt; 388&lt;p&gt;Alas, that does not compile either! It errors out with the following message:&lt;/p&gt;
261&lt;pre&gt;&lt;code&gt;error[E0562]: `impl Trait` not allowed outside of function 389&lt;pre&gt;&lt;code&gt;error[E0562]: `impl Trait` not allowed outside of function
262and inherent method return types 390and inherent method return types
@@ -267,15 +395,15 @@ and inherent method return types
267&lt;/code&gt;&lt;/pre&gt; 395&lt;/code&gt;&lt;/pre&gt;
268&lt;p&gt;You are allowed to return an &lt;code&gt;impl Fn&lt;/code&gt; only inside a function. We are currently returning it from another return! Or at least, that was the most I could make out of the error message.&lt;/p&gt; 396&lt;p&gt;You are allowed to return an &lt;code&gt;impl Fn&lt;/code&gt; only inside a function. We are currently returning it from another return! Or at least, that was the most I could make out of the error message.&lt;/p&gt;
269&lt;p&gt;We are going to have to cheat a bit to fix this issue; with type aliases and a convenient nightly feature &lt;a href="#fn2" class="footnote-ref" id="fnref2" role="doc-noteref"&gt;&lt;sup&gt;2&lt;/sup&gt;&lt;/a&gt;:&lt;/p&gt; 397&lt;p&gt;We are going to have to cheat a bit to fix this issue; with type aliases and a convenient nightly feature &lt;a href="#fn2" class="footnote-ref" id="fnref2" role="doc-noteref"&gt;&lt;sup&gt;2&lt;/sup&gt;&lt;/a&gt;:&lt;/p&gt;
270&lt;div class="sourceCode" id="cb10"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb10-1"&gt;&lt;a href="#cb10-1"&gt;&lt;/a&gt;&lt;span class="at"&gt;#![&lt;/span&gt;feature&lt;span class="at"&gt;(&lt;/span&gt;type_alias_impl_trait&lt;span class="at"&gt;)]&lt;/span&gt; &lt;span class="co"&gt;// allows us to use `impl Fn` in type aliases!&lt;/span&gt;&lt;/span&gt; 398&lt;div class="sourceCode" id="cb10"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb10-1"&gt;&lt;a href="#cb10-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="at"&gt;#![&lt;/span&gt;feature&lt;span class="at"&gt;(&lt;/span&gt;type_alias_impl_trait&lt;span class="at"&gt;)]&lt;/span&gt; &lt;span class="co"&gt;// allows us to use `impl Fn` in type aliases!&lt;/span&gt;&lt;/span&gt;
271&lt;span id="cb10-2"&gt;&lt;a href="#cb10-2"&gt;&lt;/a&gt;&lt;/span&gt; 399&lt;span id="cb10-2"&gt;&lt;a href="#cb10-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
272&lt;span id="cb10-3"&gt;&lt;a href="#cb10-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 = &lt;span class="dt"&gt;u32&lt;/span&gt;; &lt;span class="co"&gt;// the return value when zero args are to be applied&lt;/span&gt;&lt;/span&gt; 400&lt;span id="cb10-3"&gt;&lt;a href="#cb10-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// the return value when zero args are to be applied&lt;/span&gt;&lt;/span&gt;
273&lt;span id="cb10-4"&gt;&lt;a href="#cb10-4"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T1 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; T0; &lt;span class="co"&gt;// the return value when one arg is to be applied&lt;/span&gt;&lt;/span&gt; 401&lt;span id="cb10-4"&gt;&lt;a href="#cb10-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T1 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; T0&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// the return value when one arg is to be applied&lt;/span&gt;&lt;/span&gt;
274&lt;span id="cb10-5"&gt;&lt;a href="#cb10-5"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T2 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; T1; &lt;span class="co"&gt;// the return value when two args are to be applied&lt;/span&gt;&lt;/span&gt; 402&lt;span id="cb10-5"&gt;&lt;a href="#cb10-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T2 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; T1&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// the return value when two args are to be applied&lt;/span&gt;&lt;/span&gt;
275&lt;span id="cb10-6"&gt;&lt;a href="#cb10-6"&gt;&lt;/a&gt;&lt;/span&gt; 403&lt;span id="cb10-6"&gt;&lt;a href="#cb10-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
276&lt;span id="cb10-7"&gt;&lt;a href="#cb10-7"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x: &lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; T2 &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 404&lt;span id="cb10-7"&gt;&lt;a href="#cb10-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; T2 &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
277&lt;span id="cb10-8"&gt;&lt;a href="#cb10-8"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; |y| &lt;span class="kw"&gt;move&lt;/span&gt; |z| x + y + z;&lt;/span&gt; 405&lt;span id="cb10-8"&gt;&lt;a href="#cb10-8" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;y&lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;z&lt;span class="op"&gt;|&lt;/span&gt; x &lt;span class="op"&gt;+&lt;/span&gt; y &lt;span class="op"&gt;+&lt;/span&gt; z&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
278&lt;span id="cb10-9"&gt;&lt;a href="#cb10-9"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 406&lt;span id="cb10-9"&gt;&lt;a href="#cb10-9" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
279&lt;p&gt;Drop that into a cargo project, call &lt;code&gt;add(4)(5)(6)&lt;/code&gt;, cross your fingers, and run &lt;code&gt;cargo +nightly run&lt;/code&gt;. You should see a 15 unless you forgot to print it!&lt;/p&gt; 407&lt;p&gt;Drop that into a cargo project, call &lt;code&gt;add(4)(5)(6)&lt;/code&gt;, cross your fingers, and run &lt;code&gt;cargo +nightly run&lt;/code&gt;. You should see a 15 unless you forgot to print it!&lt;/p&gt;
280&lt;h3 id="the-in-betweens"&gt;The In-Betweens&lt;/h3&gt; 408&lt;h3 id="the-in-betweens"&gt;The In-Betweens&lt;/h3&gt;
281&lt;p&gt;Let us write the magical bits that take us from function to curried function.&lt;/p&gt; 409&lt;p&gt;Let us write the magical bits that take us from function to curried function.&lt;/p&gt;
@@ -309,19 +437,19 @@ proc-macro = true # this is important!&lt;/code&gt;&lt;/pre&gt;
309&lt;p&gt;We will be using an external &lt;code&gt;proc-macro2&lt;/code&gt; crate as well as an internal &lt;code&gt;proc-macro&lt;/code&gt; crate. Not confusing at all!&lt;/p&gt; 437&lt;p&gt;We will be using an external &lt;code&gt;proc-macro2&lt;/code&gt; crate as well as an internal &lt;code&gt;proc-macro&lt;/code&gt; crate. Not confusing at all!&lt;/p&gt;
310&lt;h4 id="the-attribute-macro"&gt;The attribute macro&lt;/h4&gt; 438&lt;h4 id="the-attribute-macro"&gt;The attribute macro&lt;/h4&gt;
311&lt;p&gt;Drop this into &lt;code&gt;src/lib.rs&lt;/code&gt;, to get the ball rolling.&lt;/p&gt; 439&lt;p&gt;Drop this into &lt;code&gt;src/lib.rs&lt;/code&gt;, to get the ball rolling.&lt;/p&gt;
312&lt;div class="sourceCode" id="cb13"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb13-1"&gt;&lt;a href="#cb13-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt; 440&lt;div class="sourceCode" id="cb13"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb13-1"&gt;&lt;a href="#cb13-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt;
313&lt;span id="cb13-2"&gt;&lt;a href="#cb13-2"&gt;&lt;/a&gt;&lt;/span&gt; 441&lt;span id="cb13-2"&gt;&lt;a href="#cb13-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
314&lt;span id="cb13-3"&gt;&lt;a href="#cb13-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;proc_macro::&lt;/span&gt;TokenStream; &lt;span class="co"&gt;// 1&lt;/span&gt;&lt;/span&gt; 442&lt;span id="cb13-3"&gt;&lt;a href="#cb13-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;proc_macro::&lt;/span&gt;TokenStream&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// 1&lt;/span&gt;&lt;/span&gt;
315&lt;span id="cb13-4"&gt;&lt;a href="#cb13-4"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;quote::&lt;/span&gt;quote;&lt;/span&gt; 443&lt;span id="cb13-4"&gt;&lt;a href="#cb13-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;quote::&lt;/span&gt;quote&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
316&lt;span id="cb13-5"&gt;&lt;a href="#cb13-5"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;syn::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;parse_macro_input, ItemFn&lt;span class="op"&gt;}&lt;/span&gt;;&lt;/span&gt; 444&lt;span id="cb13-5"&gt;&lt;a href="#cb13-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;syn::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;parse_macro_input&lt;span class="op"&gt;,&lt;/span&gt; ItemFn&lt;span class="op"&gt;};&lt;/span&gt;&lt;/span&gt;
317&lt;span id="cb13-6"&gt;&lt;a href="#cb13-6"&gt;&lt;/a&gt;&lt;/span&gt; 445&lt;span id="cb13-6"&gt;&lt;a href="#cb13-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
318&lt;span id="cb13-7"&gt;&lt;a href="#cb13-7"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;proc_macro_attribute&lt;span class="at"&gt;]&lt;/span&gt; &lt;span class="co"&gt;// 2&lt;/span&gt;&lt;/span&gt; 446&lt;span id="cb13-7"&gt;&lt;a href="#cb13-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;proc_macro_attribute&lt;span class="at"&gt;]&lt;/span&gt; &lt;span class="co"&gt;// 2&lt;/span&gt;&lt;/span&gt;
319&lt;span id="cb13-8"&gt;&lt;a href="#cb13-8"&gt;&lt;/a&gt;&lt;span class="kw"&gt;pub&lt;/span&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; curry(_attr: TokenStream, item: TokenStream) -&amp;gt; TokenStream &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 447&lt;span id="cb13-8"&gt;&lt;a href="#cb13-8" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;pub&lt;/span&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; curry(_attr&lt;span class="op"&gt;:&lt;/span&gt; TokenStream&lt;span class="op"&gt;,&lt;/span&gt; item&lt;span class="op"&gt;:&lt;/span&gt; TokenStream) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; TokenStream &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
320&lt;span id="cb13-9"&gt;&lt;a href="#cb13-9"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; parsed = &lt;span class="pp"&gt;parse_macro_input!&lt;/span&gt;(item &lt;span class="kw"&gt;as&lt;/span&gt; ItemFn); &lt;span class="co"&gt;// 3&lt;/span&gt;&lt;/span&gt; 448&lt;span id="cb13-9"&gt;&lt;a href="#cb13-9" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; parsed &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="pp"&gt;parse_macro_input!&lt;/span&gt;(item &lt;span class="kw"&gt;as&lt;/span&gt; ItemFn)&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// 3&lt;/span&gt;&lt;/span&gt;
321&lt;span id="cb13-10"&gt;&lt;a href="#cb13-10"&gt;&lt;/a&gt; generate_curry(parsed).into() &lt;span class="co"&gt;// 4&lt;/span&gt;&lt;/span&gt; 449&lt;span id="cb13-10"&gt;&lt;a href="#cb13-10" aria-hidden="true"&gt;&lt;/a&gt; generate_curry(parsed)&lt;span class="op"&gt;.&lt;/span&gt;into() &lt;span class="co"&gt;// 4&lt;/span&gt;&lt;/span&gt;
322&lt;span id="cb13-11"&gt;&lt;a href="#cb13-11"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 450&lt;span id="cb13-11"&gt;&lt;a href="#cb13-11" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
323&lt;span id="cb13-12"&gt;&lt;a href="#cb13-12"&gt;&lt;/a&gt;&lt;/span&gt; 451&lt;span id="cb13-12"&gt;&lt;a href="#cb13-12" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
324&lt;span id="cb13-13"&gt;&lt;a href="#cb13-13"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; generate_curry(parsed: ItemFn) -&amp;gt; &lt;span class="pp"&gt;proc_macro2::&lt;/span&gt;TokenStream &lt;span class="op"&gt;{}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 452&lt;span id="cb13-13"&gt;&lt;a href="#cb13-13" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; generate_curry(parsed&lt;span class="op"&gt;:&lt;/span&gt; ItemFn) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="pp"&gt;proc_macro2::&lt;/span&gt;TokenStream &lt;span class="op"&gt;{}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
325&lt;p&gt;&lt;strong&gt;1. Imports&lt;/strong&gt;&lt;/p&gt; 453&lt;p&gt;&lt;strong&gt;1. Imports&lt;/strong&gt;&lt;/p&gt;
326&lt;p&gt;A &lt;code&gt;Tokenstream&lt;/code&gt; holds (hopefully valid) Rust code, this is the type of our input and output. Note that we are importing this type from &lt;code&gt;proc_macro&lt;/code&gt; and not &lt;code&gt;proc_macro2&lt;/code&gt;.&lt;/p&gt; 454&lt;p&gt;A &lt;code&gt;Tokenstream&lt;/code&gt; holds (hopefully valid) Rust code, this is the type of our input and output. Note that we are importing this type from &lt;code&gt;proc_macro&lt;/code&gt; and not &lt;code&gt;proc_macro2&lt;/code&gt;.&lt;/p&gt;
327&lt;p&gt;&lt;code&gt;quote!&lt;/code&gt; from the &lt;code&gt;quote&lt;/code&gt; crate is a macro that allows us to quickly produce &lt;code&gt;TokenStream&lt;/code&gt;s. Much like the LISP &lt;code&gt;quote&lt;/code&gt; procedure, you can use the &lt;code&gt;quote!&lt;/code&gt; macro for symbolic transformations.&lt;/p&gt; 455&lt;p&gt;&lt;code&gt;quote!&lt;/code&gt; from the &lt;code&gt;quote&lt;/code&gt; crate is a macro that allows us to quickly produce &lt;code&gt;TokenStream&lt;/code&gt;s. Much like the LISP &lt;code&gt;quote&lt;/code&gt; procedure, you can use the &lt;code&gt;quote!&lt;/code&gt; macro for symbolic transformations.&lt;/p&gt;
@@ -333,16 +461,16 @@ proc-macro = true # this is important!&lt;/code&gt;&lt;/pre&gt;
333&lt;p&gt;&lt;strong&gt;4. Returning &lt;code&gt;TokenStream&lt;/code&gt;s &lt;/strong&gt;&lt;/p&gt; 461&lt;p&gt;&lt;strong&gt;4. Returning &lt;code&gt;TokenStream&lt;/code&gt;s &lt;/strong&gt;&lt;/p&gt;
334&lt;p&gt;We haven’t filled in &lt;code&gt;generate_curry&lt;/code&gt; yet, but we can see that it returns a &lt;code&gt;proc_macro2::TokenStream&lt;/code&gt; and not a &lt;code&gt;proc_macro::TokenStream&lt;/code&gt;, so drop a &lt;code&gt;.into()&lt;/code&gt; to convert it.&lt;/p&gt; 462&lt;p&gt;We haven’t filled in &lt;code&gt;generate_curry&lt;/code&gt; yet, but we can see that it returns a &lt;code&gt;proc_macro2::TokenStream&lt;/code&gt; and not a &lt;code&gt;proc_macro::TokenStream&lt;/code&gt;, so drop a &lt;code&gt;.into()&lt;/code&gt; to convert it.&lt;/p&gt;
335&lt;p&gt;Lets move on, and fill in &lt;code&gt;generate_curry&lt;/code&gt;, I would suggest keeping the documentation for &lt;a href="https://docs.rs/syn/1.0.19/syn/struct.ItemFn.html"&gt;&lt;code&gt;syn::ItemFn&lt;/code&gt;&lt;/a&gt; and &lt;a href="https://docs.rs/syn/1.0.19/syn/struct.Signature.html"&gt;&lt;code&gt;syn::Signature&lt;/code&gt;&lt;/a&gt; open.&lt;/p&gt; 463&lt;p&gt;Lets move on, and fill in &lt;code&gt;generate_curry&lt;/code&gt;, I would suggest keeping the documentation for &lt;a href="https://docs.rs/syn/1.0.19/syn/struct.ItemFn.html"&gt;&lt;code&gt;syn::ItemFn&lt;/code&gt;&lt;/a&gt; and &lt;a href="https://docs.rs/syn/1.0.19/syn/struct.Signature.html"&gt;&lt;code&gt;syn::Signature&lt;/code&gt;&lt;/a&gt; open.&lt;/p&gt;
336&lt;div class="sourceCode" id="cb14"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb14-1"&gt;&lt;a href="#cb14-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt; 464&lt;div class="sourceCode" id="cb14"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb14-1"&gt;&lt;a href="#cb14-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt;
337&lt;span id="cb14-2"&gt;&lt;a href="#cb14-2"&gt;&lt;/a&gt;&lt;/span&gt; 465&lt;span id="cb14-2"&gt;&lt;a href="#cb14-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
338&lt;span id="cb14-3"&gt;&lt;a href="#cb14-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; generate_curry(parsed: ItemFn) -&amp;gt; &lt;span class="pp"&gt;proc_macro2::&lt;/span&gt;TokenStream &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 466&lt;span id="cb14-3"&gt;&lt;a href="#cb14-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; generate_curry(parsed&lt;span class="op"&gt;:&lt;/span&gt; ItemFn) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="pp"&gt;proc_macro2::&lt;/span&gt;TokenStream &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
339&lt;span id="cb14-4"&gt;&lt;a href="#cb14-4"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_body = parsed.block; &lt;span class="co"&gt;// function body&lt;/span&gt;&lt;/span&gt; 467&lt;span id="cb14-4"&gt;&lt;a href="#cb14-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_body &lt;span class="op"&gt;=&lt;/span&gt; parsed&lt;span class="op"&gt;.&lt;/span&gt;block&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// function body&lt;/span&gt;&lt;/span&gt;
340&lt;span id="cb14-5"&gt;&lt;a href="#cb14-5"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; sig = parsed.sig; &lt;span class="co"&gt;// function signature&lt;/span&gt;&lt;/span&gt; 468&lt;span id="cb14-5"&gt;&lt;a href="#cb14-5" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; sig &lt;span class="op"&gt;=&lt;/span&gt; parsed&lt;span class="op"&gt;.&lt;/span&gt;sig&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// function signature&lt;/span&gt;&lt;/span&gt;
341&lt;span id="cb14-6"&gt;&lt;a href="#cb14-6"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; vis = parsed.vis; &lt;span class="co"&gt;// visibility, pub or not&lt;/span&gt;&lt;/span&gt; 469&lt;span id="cb14-6"&gt;&lt;a href="#cb14-6" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; vis &lt;span class="op"&gt;=&lt;/span&gt; parsed&lt;span class="op"&gt;.&lt;/span&gt;vis&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// visibility, pub or not&lt;/span&gt;&lt;/span&gt;
342&lt;span id="cb14-7"&gt;&lt;a href="#cb14-7"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_name = sig.ident; &lt;span class="co"&gt;// function name/identifier&lt;/span&gt;&lt;/span&gt; 470&lt;span id="cb14-7"&gt;&lt;a href="#cb14-7" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_name &lt;span class="op"&gt;=&lt;/span&gt; sig&lt;span class="op"&gt;.&lt;/span&gt;ident&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// function name/identifier&lt;/span&gt;&lt;/span&gt;
343&lt;span id="cb14-8"&gt;&lt;a href="#cb14-8"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_args = sig.inputs; &lt;span class="co"&gt;// comma separated args&lt;/span&gt;&lt;/span&gt; 471&lt;span id="cb14-8"&gt;&lt;a href="#cb14-8" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_args &lt;span class="op"&gt;=&lt;/span&gt; sig&lt;span class="op"&gt;.&lt;/span&gt;inputs&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// comma separated args&lt;/span&gt;&lt;/span&gt;
344&lt;span id="cb14-9"&gt;&lt;a href="#cb14-9"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_return_type = sig.output; &lt;span class="co"&gt;// return type&lt;/span&gt;&lt;/span&gt; 472&lt;span id="cb14-9"&gt;&lt;a href="#cb14-9" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_return_type &lt;span class="op"&gt;=&lt;/span&gt; sig&lt;span class="op"&gt;.&lt;/span&gt;output&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// return type&lt;/span&gt;&lt;/span&gt;
345&lt;span id="cb14-10"&gt;&lt;a href="#cb14-10"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 473&lt;span id="cb14-10"&gt;&lt;a href="#cb14-10" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
346&lt;p&gt;We are simply extracting the bits of the function, we will be reusing the original function’s visibility and name. Take a look at what &lt;code&gt;syn::Signature&lt;/code&gt; can tell us about a function:&lt;/p&gt; 474&lt;p&gt;We are simply extracting the bits of the function, we will be reusing the original function’s visibility and name. Take a look at what &lt;code&gt;syn::Signature&lt;/code&gt; can tell us about a function:&lt;/p&gt;
347&lt;pre&gt;&lt;code&gt; .-- syn::Ident (ident) 475&lt;pre&gt;&lt;code&gt; .-- syn::Ident (ident)
348 / 476 /
@@ -354,220 +482,220 @@ syn::token::Fn --&amp;#39; / \ (output)
354&lt;p&gt;Enough analysis, lets produce our first bit of Rust code.&lt;/p&gt; 482&lt;p&gt;Enough analysis, lets produce our first bit of Rust code.&lt;/p&gt;
355&lt;h4 id="function-body"&gt;Function Body&lt;/h4&gt; 483&lt;h4 id="function-body"&gt;Function Body&lt;/h4&gt;
356&lt;p&gt;Recall that the body of a curried &lt;code&gt;add&lt;/code&gt; should look like this:&lt;/p&gt; 484&lt;p&gt;Recall that the body of a curried &lt;code&gt;add&lt;/code&gt; should look like this:&lt;/p&gt;
357&lt;div class="sourceCode" id="cb16"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb16-1"&gt;&lt;a href="#cb16-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; |y| &lt;span class="kw"&gt;move&lt;/span&gt; |z| x + y + z;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 485&lt;div class="sourceCode" id="cb16"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb16-1"&gt;&lt;a href="#cb16-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;y&lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;z&lt;span class="op"&gt;|&lt;/span&gt; x &lt;span class="op"&gt;+&lt;/span&gt; y &lt;span class="op"&gt;+&lt;/span&gt; z&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
358&lt;p&gt;And in general:&lt;/p&gt; 486&lt;p&gt;And in general:&lt;/p&gt;
359&lt;div class="sourceCode" id="cb17"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb17-1"&gt;&lt;a href="#cb17-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; |arg2| &lt;span class="kw"&gt;move&lt;/span&gt; |arg3| ... |argN| &amp;lt;function body here&amp;gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 487&lt;div class="sourceCode" id="cb17"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb17-1"&gt;&lt;a href="#cb17-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;arg2&lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="kw"&gt;move&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;arg3&lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="op"&gt;...&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;argN&lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="op"&gt;&amp;lt;&lt;/span&gt;function body here&lt;span class="op"&gt;&amp;gt;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
360&lt;p&gt;We already have the function’s body, provided by &lt;code&gt;fn_body&lt;/code&gt;, in our &lt;code&gt;generate_curry&lt;/code&gt; function. All that’s left to add is the &lt;code&gt;move |arg2| move |arg3| ...&lt;/code&gt; stuff, for which we need to extract the argument identifiers (doc: &lt;a href="https://docs.rs/syn/1.0.18/syn/punctuated/struct.Punctuated.html"&gt;Punctuated&lt;/a&gt;, &lt;a href="https://docs.rs/syn/1.0.18/syn/enum.FnArg.html"&gt;FnArg&lt;/a&gt;, &lt;a href="https://docs.rs/syn/1.0.18/syn/struct.PatType.html"&gt;PatType&lt;/a&gt;):&lt;/p&gt; 488&lt;p&gt;We already have the function’s body, provided by &lt;code&gt;fn_body&lt;/code&gt;, in our &lt;code&gt;generate_curry&lt;/code&gt; function. All that’s left to add is the &lt;code&gt;move |arg2| move |arg3| ...&lt;/code&gt; stuff, for which we need to extract the argument identifiers (doc: &lt;a href="https://docs.rs/syn/1.0.18/syn/punctuated/struct.Punctuated.html"&gt;Punctuated&lt;/a&gt;, &lt;a href="https://docs.rs/syn/1.0.18/syn/enum.FnArg.html"&gt;FnArg&lt;/a&gt;, &lt;a href="https://docs.rs/syn/1.0.18/syn/struct.PatType.html"&gt;PatType&lt;/a&gt;):&lt;/p&gt;
361&lt;div class="sourceCode" id="cb18"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb18-1"&gt;&lt;a href="#cb18-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt; 489&lt;div class="sourceCode" id="cb18"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb18-1"&gt;&lt;a href="#cb18-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt;
362&lt;span id="cb18-2"&gt;&lt;a href="#cb18-2"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;syn::punctuated::&lt;/span&gt;Punctuated;&lt;/span&gt; 490&lt;span id="cb18-2"&gt;&lt;a href="#cb18-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;syn::punctuated::&lt;/span&gt;Punctuated&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
363&lt;span id="cb18-3"&gt;&lt;a href="#cb18-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;syn::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;parse_macro_input, FnArg, Pat, ItemFn, Block&lt;span class="op"&gt;}&lt;/span&gt;;&lt;/span&gt; 491&lt;span id="cb18-3"&gt;&lt;a href="#cb18-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;syn::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;parse_macro_input&lt;span class="op"&gt;,&lt;/span&gt; FnArg&lt;span class="op"&gt;,&lt;/span&gt; Pat&lt;span class="op"&gt;,&lt;/span&gt; ItemFn&lt;span class="op"&gt;,&lt;/span&gt; Block&lt;span class="op"&gt;};&lt;/span&gt;&lt;/span&gt;
364&lt;span id="cb18-4"&gt;&lt;a href="#cb18-4"&gt;&lt;/a&gt;&lt;/span&gt; 492&lt;span id="cb18-4"&gt;&lt;a href="#cb18-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
365&lt;span id="cb18-5"&gt;&lt;a href="#cb18-5"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; extract_arg_idents(fn_args: Punctuated&amp;lt;FnArg, &lt;span class="pp"&gt;syn::token::&lt;/span&gt;Comma&amp;gt;) -&amp;gt; &lt;span class="dt"&gt;Vec&lt;/span&gt;&amp;lt;&lt;span class="dt"&gt;Box&lt;/span&gt;&amp;lt;Pat&amp;gt;&amp;gt; &lt;span class="op"&gt;{&lt;/span&gt; &lt;/span&gt; 493&lt;span id="cb18-5"&gt;&lt;a href="#cb18-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; extract_arg_idents(fn_args&lt;span class="op"&gt;:&lt;/span&gt; Punctuated&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;FnArg&lt;span class="op"&gt;,&lt;/span&gt; &lt;span class="pp"&gt;syn::token::&lt;/span&gt;Comma&lt;span class="op"&gt;&amp;gt;&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;Vec&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="dt"&gt;Box&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;Pat&lt;span class="op"&gt;&amp;gt;&amp;gt;&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt; &lt;/span&gt;
366&lt;span id="cb18-6"&gt;&lt;a href="#cb18-6"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; fn_args.into_iter().map(extract_arg_pat).&lt;span class="pp"&gt;collect::&lt;/span&gt;&amp;lt;&lt;span class="dt"&gt;Vec&lt;/span&gt;&amp;lt;_&amp;gt;&amp;gt;();&lt;/span&gt; 494&lt;span id="cb18-6"&gt;&lt;a href="#cb18-6" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; fn_args&lt;span class="op"&gt;.&lt;/span&gt;into_iter()&lt;span class="op"&gt;.&lt;/span&gt;map(extract_arg_pat)&lt;span class="op"&gt;.&lt;/span&gt;&lt;span class="pp"&gt;collect::&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="dt"&gt;Vec&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;_&lt;span class="op"&gt;&amp;gt;&amp;gt;&lt;/span&gt;()&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
367&lt;span id="cb18-7"&gt;&lt;a href="#cb18-7"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 495&lt;span id="cb18-7"&gt;&lt;a href="#cb18-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
368&lt;p&gt;Alright, so we are iterating over function args (&lt;code&gt;Punctuated&lt;/code&gt; is a collection that you can iterate over) and mapping an &lt;code&gt;extract_arg_pat&lt;/code&gt; to every item. What’s &lt;code&gt;extract_arg_pat&lt;/code&gt;?&lt;/p&gt; 496&lt;p&gt;Alright, so we are iterating over function args (&lt;code&gt;Punctuated&lt;/code&gt; is a collection that you can iterate over) and mapping an &lt;code&gt;extract_arg_pat&lt;/code&gt; to every item. What’s &lt;code&gt;extract_arg_pat&lt;/code&gt;?&lt;/p&gt;
369&lt;div class="sourceCode" id="cb19"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb19-1"&gt;&lt;a href="#cb19-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt; 497&lt;div class="sourceCode" id="cb19"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb19-1"&gt;&lt;a href="#cb19-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt;
370&lt;span id="cb19-2"&gt;&lt;a href="#cb19-2"&gt;&lt;/a&gt;&lt;/span&gt; 498&lt;span id="cb19-2"&gt;&lt;a href="#cb19-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
371&lt;span id="cb19-3"&gt;&lt;a href="#cb19-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; extract_arg_pat(a: FnArg) -&amp;gt; &lt;span class="dt"&gt;Box&lt;/span&gt;&amp;lt;Pat&amp;gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 499&lt;span id="cb19-3"&gt;&lt;a href="#cb19-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; extract_arg_pat(a&lt;span class="op"&gt;:&lt;/span&gt; FnArg) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;Box&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;Pat&lt;span class="op"&gt;&amp;gt;&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
372&lt;span id="cb19-4"&gt;&lt;a href="#cb19-4"&gt;&lt;/a&gt; &lt;span class="kw"&gt;match&lt;/span&gt; a &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 500&lt;span id="cb19-4"&gt;&lt;a href="#cb19-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;match&lt;/span&gt; a &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
373&lt;span id="cb19-5"&gt;&lt;a href="#cb19-5"&gt;&lt;/a&gt; &lt;span class="pp"&gt;FnArg::&lt;/span&gt;Typed(p) =&amp;gt; p.pat,&lt;/span&gt; 501&lt;span id="cb19-5"&gt;&lt;a href="#cb19-5" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="pp"&gt;FnArg::&lt;/span&gt;Typed(p) &lt;span class="op"&gt;=&amp;gt;&lt;/span&gt; p&lt;span class="op"&gt;.&lt;/span&gt;pat&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
374&lt;span id="cb19-6"&gt;&lt;a href="#cb19-6"&gt;&lt;/a&gt; _ =&amp;gt; &lt;span class="pp"&gt;panic!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;Not supported on types with `self`!&amp;quot;&lt;/span&gt;),&lt;/span&gt; 502&lt;span id="cb19-6"&gt;&lt;a href="#cb19-6" aria-hidden="true"&gt;&lt;/a&gt; _ &lt;span class="op"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="pp"&gt;panic!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;Not supported on types with `self`!&amp;quot;&lt;/span&gt;)&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
375&lt;span id="cb19-7"&gt;&lt;a href="#cb19-7"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 503&lt;span id="cb19-7"&gt;&lt;a href="#cb19-7" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
376&lt;span id="cb19-8"&gt;&lt;a href="#cb19-8"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 504&lt;span id="cb19-8"&gt;&lt;a href="#cb19-8" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
377&lt;p&gt;&lt;code&gt;FnArg&lt;/code&gt; is an enum type as you might have guessed. The &lt;code&gt;Typed&lt;/code&gt; variant encompasses args that are written as &lt;code&gt;name: type&lt;/code&gt; and the other variant, &lt;code&gt;Reciever&lt;/code&gt; refers to &lt;code&gt;self&lt;/code&gt; types. Ignore those for now, keep it simple.&lt;/p&gt; 505&lt;p&gt;&lt;code&gt;FnArg&lt;/code&gt; is an enum type as you might have guessed. The &lt;code&gt;Typed&lt;/code&gt; variant encompasses args that are written as &lt;code&gt;name: type&lt;/code&gt; and the other variant, &lt;code&gt;Reciever&lt;/code&gt; refers to &lt;code&gt;self&lt;/code&gt; types. Ignore those for now, keep it simple.&lt;/p&gt;
378&lt;p&gt;Every &lt;code&gt;FnArg::Typed&lt;/code&gt; value contains a &lt;code&gt;pat&lt;/code&gt;, which is in essence, the name of the argument. The type of the arg is accessible via &lt;code&gt;p.ty&lt;/code&gt; (we will be using this later).&lt;/p&gt; 506&lt;p&gt;Every &lt;code&gt;FnArg::Typed&lt;/code&gt; value contains a &lt;code&gt;pat&lt;/code&gt;, which is in essence, the name of the argument. The type of the arg is accessible via &lt;code&gt;p.ty&lt;/code&gt; (we will be using this later).&lt;/p&gt;
379&lt;p&gt;With that done, we should be able to write the codegen for the function body:&lt;/p&gt; 507&lt;p&gt;With that done, we should be able to write the codegen for the function body:&lt;/p&gt;
380&lt;div class="sourceCode" id="cb20"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb20-1"&gt;&lt;a href="#cb20-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt; 508&lt;div class="sourceCode" id="cb20"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb20-1"&gt;&lt;a href="#cb20-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt;
381&lt;span id="cb20-2"&gt;&lt;a href="#cb20-2"&gt;&lt;/a&gt;&lt;/span&gt; 509&lt;span id="cb20-2"&gt;&lt;a href="#cb20-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
382&lt;span id="cb20-3"&gt;&lt;a href="#cb20-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; generate_body(fn_args: &amp;amp;&lt;span class="op"&gt;[&lt;/span&gt;&lt;span class="dt"&gt;Box&lt;/span&gt;&amp;lt;Pat&amp;gt;&lt;span class="op"&gt;]&lt;/span&gt;, body: &lt;span class="dt"&gt;Box&lt;/span&gt;&amp;lt;Block&amp;gt;) -&amp;gt; &lt;span class="pp"&gt;proc_macro2::&lt;/span&gt;TokenStream &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 510&lt;span id="cb20-3"&gt;&lt;a href="#cb20-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; generate_body(fn_args&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="op"&gt;&amp;amp;&lt;/span&gt;[&lt;span class="dt"&gt;Box&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;Pat&lt;span class="op"&gt;&amp;gt;&lt;/span&gt;]&lt;span class="op"&gt;,&lt;/span&gt; body&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;Box&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;Block&lt;span class="op"&gt;&amp;gt;&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="pp"&gt;proc_macro2::&lt;/span&gt;TokenStream &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
383&lt;span id="cb20-4"&gt;&lt;a href="#cb20-4"&gt;&lt;/a&gt; &lt;span class="pp"&gt;quote!&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 511&lt;span id="cb20-4"&gt;&lt;a href="#cb20-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="pp"&gt;quote!&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
384&lt;span id="cb20-5"&gt;&lt;a href="#cb20-5"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; #( &lt;span class="kw"&gt;move&lt;/span&gt; |#fn_args| )* #body&lt;/span&gt; 512&lt;span id="cb20-5"&gt;&lt;a href="#cb20-5" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; #( &lt;span class="kw"&gt;move&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;#fn_args&lt;span class="op"&gt;|&lt;/span&gt; )&lt;span class="op"&gt;*&lt;/span&gt; #body&lt;/span&gt;
385&lt;span id="cb20-6"&gt;&lt;a href="#cb20-6"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 513&lt;span id="cb20-6"&gt;&lt;a href="#cb20-6" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
386&lt;span id="cb20-7"&gt;&lt;a href="#cb20-7"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 514&lt;span id="cb20-7"&gt;&lt;a href="#cb20-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
387&lt;p&gt;That is some scary looking syntax! Allow me to explain. The &lt;code&gt;quote!{ ... }&lt;/code&gt; returns a &lt;code&gt;proc_macro2::TokenStream&lt;/code&gt;, if we wrote &lt;code&gt;quote!{ let x = 1 + 2; }&lt;/code&gt;, it wouldn’t create a new variable &lt;code&gt;x&lt;/code&gt; with value 3, it would literally produce a stream of tokens with that expression.&lt;/p&gt; 515&lt;p&gt;That is some scary looking syntax! Allow me to explain. The &lt;code&gt;quote!{ ... }&lt;/code&gt; returns a &lt;code&gt;proc_macro2::TokenStream&lt;/code&gt;, if we wrote &lt;code&gt;quote!{ let x = 1 + 2; }&lt;/code&gt;, it wouldn’t create a new variable &lt;code&gt;x&lt;/code&gt; with value 3, it would literally produce a stream of tokens with that expression.&lt;/p&gt;
388&lt;p&gt;The &lt;code&gt;#&lt;/code&gt; enables variable interpolation. &lt;code&gt;#body&lt;/code&gt; will look for &lt;code&gt;body&lt;/code&gt; in the current scope, take its value, and insert it in the returned &lt;code&gt;TokenStream&lt;/code&gt;. Kinda like quasi quoting in LISPs, you have written one.&lt;/p&gt; 516&lt;p&gt;The &lt;code&gt;#&lt;/code&gt; enables variable interpolation. &lt;code&gt;#body&lt;/code&gt; will look for &lt;code&gt;body&lt;/code&gt; in the current scope, take its value, and insert it in the returned &lt;code&gt;TokenStream&lt;/code&gt;. Kinda like quasi quoting in LISPs, you have written one.&lt;/p&gt;
389&lt;p&gt;What about &lt;code&gt;#( move |#fn_args| )*&lt;/code&gt;? That is repetition. &lt;code&gt;quote&lt;/code&gt; iterates through &lt;code&gt;fn_args&lt;/code&gt;, and drops a &lt;code&gt;move&lt;/code&gt; behind each one, it then places pipes (&lt;code&gt;|&lt;/code&gt;), around it.&lt;/p&gt; 517&lt;p&gt;What about &lt;code&gt;#( move |#fn_args| )*&lt;/code&gt;? That is repetition. &lt;code&gt;quote&lt;/code&gt; iterates through &lt;code&gt;fn_args&lt;/code&gt;, and drops a &lt;code&gt;move&lt;/code&gt; behind each one, it then places pipes (&lt;code&gt;|&lt;/code&gt;), around it.&lt;/p&gt;
390&lt;p&gt;Let us test our first bit of codegen! Modify &lt;code&gt;generate_curry&lt;/code&gt; like so:&lt;/p&gt; 518&lt;p&gt;Let us test our first bit of codegen! Modify &lt;code&gt;generate_curry&lt;/code&gt; like so:&lt;/p&gt;
391&lt;div class="sourceCode" id="cb21"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb21-1"&gt;&lt;a href="#cb21-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt; 519&lt;div class="sourceCode" id="cb21"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb21-1"&gt;&lt;a href="#cb21-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt;
392&lt;span id="cb21-2"&gt;&lt;a href="#cb21-2"&gt;&lt;/a&gt;&lt;/span&gt; 520&lt;span id="cb21-2"&gt;&lt;a href="#cb21-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
393&lt;span id="cb21-3"&gt;&lt;a href="#cb21-3"&gt;&lt;/a&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; generate_curry(parsed: ItemFn) -&amp;gt; TokenStream &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 521&lt;span id="cb21-3"&gt;&lt;a href="#cb21-3" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; generate_curry(parsed&lt;span class="op"&gt;:&lt;/span&gt; ItemFn) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; TokenStream &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
394&lt;span id="cb21-4"&gt;&lt;a href="#cb21-4"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_body = parsed.block;&lt;/span&gt; 522&lt;span id="cb21-4"&gt;&lt;a href="#cb21-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_body &lt;span class="op"&gt;=&lt;/span&gt; parsed&lt;span class="op"&gt;.&lt;/span&gt;block&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
395&lt;span id="cb21-5"&gt;&lt;a href="#cb21-5"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; sig = parsed.sig;&lt;/span&gt; 523&lt;span id="cb21-5"&gt;&lt;a href="#cb21-5" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; sig &lt;span class="op"&gt;=&lt;/span&gt; parsed&lt;span class="op"&gt;.&lt;/span&gt;sig&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
396&lt;span id="cb21-6"&gt;&lt;a href="#cb21-6"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; vis = parsed.vis;&lt;/span&gt; 524&lt;span id="cb21-6"&gt;&lt;a href="#cb21-6" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; vis &lt;span class="op"&gt;=&lt;/span&gt; parsed&lt;span class="op"&gt;.&lt;/span&gt;vis&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
397&lt;span id="cb21-7"&gt;&lt;a href="#cb21-7"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_name = sig.ident;&lt;/span&gt; 525&lt;span id="cb21-7"&gt;&lt;a href="#cb21-7" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_name &lt;span class="op"&gt;=&lt;/span&gt; sig&lt;span class="op"&gt;.&lt;/span&gt;ident&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
398&lt;span id="cb21-8"&gt;&lt;a href="#cb21-8"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_args = sig.inputs;&lt;/span&gt; 526&lt;span id="cb21-8"&gt;&lt;a href="#cb21-8" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_args &lt;span class="op"&gt;=&lt;/span&gt; sig&lt;span class="op"&gt;.&lt;/span&gt;inputs&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
399&lt;span id="cb21-9"&gt;&lt;a href="#cb21-9"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_return_type = sig.output;&lt;/span&gt; 527&lt;span id="cb21-9"&gt;&lt;a href="#cb21-9" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_return_type &lt;span class="op"&gt;=&lt;/span&gt; sig&lt;span class="op"&gt;.&lt;/span&gt;output&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
400&lt;span id="cb21-10"&gt;&lt;a href="#cb21-10"&gt;&lt;/a&gt;&lt;/span&gt; 528&lt;span id="cb21-10"&gt;&lt;a href="#cb21-10" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
401&lt;span id="cb21-11"&gt;&lt;a href="#cb21-11"&gt;&lt;/a&gt;+ &lt;span class="kw"&gt;let&lt;/span&gt; arg_idents = extract_arg_idents(fn_args.clone());&lt;/span&gt; 529&lt;span id="cb21-11"&gt;&lt;a href="#cb21-11" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="kw"&gt;let&lt;/span&gt; arg_idents &lt;span class="op"&gt;=&lt;/span&gt; extract_arg_idents(fn_args&lt;span class="op"&gt;.&lt;/span&gt;clone())&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
402&lt;span id="cb21-12"&gt;&lt;a href="#cb21-12"&gt;&lt;/a&gt;+ &lt;span class="kw"&gt;let&lt;/span&gt; first_ident = &amp;amp;arg_idents.first().unwrap();&lt;/span&gt; 530&lt;span id="cb21-12"&gt;&lt;a href="#cb21-12" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="kw"&gt;let&lt;/span&gt; first_ident &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="op"&gt;&amp;amp;&lt;/span&gt;arg_idents&lt;span class="op"&gt;.&lt;/span&gt;first()&lt;span class="op"&gt;.&lt;/span&gt;unwrap()&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
403&lt;span id="cb21-13"&gt;&lt;a href="#cb21-13"&gt;&lt;/a&gt;&lt;/span&gt; 531&lt;span id="cb21-13"&gt;&lt;a href="#cb21-13" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
404&lt;span id="cb21-14"&gt;&lt;a href="#cb21-14"&gt;&lt;/a&gt;+ &lt;span class="co"&gt;// remember, our curried body starts with the second argument!&lt;/span&gt;&lt;/span&gt; 532&lt;span id="cb21-14"&gt;&lt;a href="#cb21-14" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="co"&gt;// remember, our curried body starts with the second argument!&lt;/span&gt;&lt;/span&gt;
405&lt;span id="cb21-15"&gt;&lt;a href="#cb21-15"&gt;&lt;/a&gt;+ &lt;span class="kw"&gt;let&lt;/span&gt; curried_body = generate_body(&amp;amp;arg_idents&lt;span class="op"&gt;[&lt;/span&gt;&lt;span class="dv"&gt;1&lt;/span&gt;..&lt;span class="op"&gt;]&lt;/span&gt;, fn_body.clone());&lt;/span&gt; 533&lt;span id="cb21-15"&gt;&lt;a href="#cb21-15" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="kw"&gt;let&lt;/span&gt; curried_body &lt;span class="op"&gt;=&lt;/span&gt; generate_body(&lt;span class="op"&gt;&amp;amp;&lt;/span&gt;arg_idents[&lt;span class="dv"&gt;1&lt;/span&gt;&lt;span class="op"&gt;..&lt;/span&gt;]&lt;span class="op"&gt;,&lt;/span&gt; fn_body&lt;span class="op"&gt;.&lt;/span&gt;clone())&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
406&lt;span id="cb21-16"&gt;&lt;a href="#cb21-16"&gt;&lt;/a&gt;+ &lt;span class="pp"&gt;println!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;{}&amp;quot;&lt;/span&gt;, curried_body);&lt;/span&gt; 534&lt;span id="cb21-16"&gt;&lt;a href="#cb21-16" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="pp"&gt;println!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;{}&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; curried_body)&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
407&lt;span id="cb21-17"&gt;&lt;a href="#cb21-17"&gt;&lt;/a&gt;&lt;/span&gt; 535&lt;span id="cb21-17"&gt;&lt;a href="#cb21-17" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
408&lt;span id="cb21-18"&gt;&lt;a href="#cb21-18"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="pp"&gt;TokenStream::&lt;/span&gt;new();&lt;/span&gt; 536&lt;span id="cb21-18"&gt;&lt;a href="#cb21-18" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="pp"&gt;TokenStream::&lt;/span&gt;new()&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
409&lt;span id="cb21-19"&gt;&lt;a href="#cb21-19"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 537&lt;span id="cb21-19"&gt;&lt;a href="#cb21-19" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
410&lt;p&gt;Add a little test to &lt;code&gt;tests/&lt;/code&gt;:&lt;/p&gt; 538&lt;p&gt;Add a little test to &lt;code&gt;tests/&lt;/code&gt;:&lt;/p&gt;
411&lt;div class="sourceCode" id="cb22"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb22-1"&gt;&lt;a href="#cb22-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// tests/smoke.rs&lt;/span&gt;&lt;/span&gt; 539&lt;div class="sourceCode" id="cb22"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb22-1"&gt;&lt;a href="#cb22-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// tests/smoke.rs&lt;/span&gt;&lt;/span&gt;
412&lt;span id="cb22-2"&gt;&lt;a href="#cb22-2"&gt;&lt;/a&gt;&lt;/span&gt; 540&lt;span id="cb22-2"&gt;&lt;a href="#cb22-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
413&lt;span id="cb22-3"&gt;&lt;a href="#cb22-3"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;&lt;span class="pp"&gt;currying::&lt;/span&gt;curry&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt; 541&lt;span id="cb22-3"&gt;&lt;a href="#cb22-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;&lt;span class="pp"&gt;currying::&lt;/span&gt;curry&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt;
414&lt;span id="cb22-4"&gt;&lt;a href="#cb22-4"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x: &lt;span class="dt"&gt;u32&lt;/span&gt;, y: &lt;span class="dt"&gt;u32&lt;/span&gt;, z: &lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 542&lt;span id="cb22-4"&gt;&lt;a href="#cb22-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; y&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; z&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
415&lt;span id="cb22-5"&gt;&lt;a href="#cb22-5"&gt;&lt;/a&gt; x + y + z&lt;/span&gt; 543&lt;span id="cb22-5"&gt;&lt;a href="#cb22-5" aria-hidden="true"&gt;&lt;/a&gt; x &lt;span class="op"&gt;+&lt;/span&gt; y &lt;span class="op"&gt;+&lt;/span&gt; z&lt;/span&gt;
416&lt;span id="cb22-6"&gt;&lt;a href="#cb22-6"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 544&lt;span id="cb22-6"&gt;&lt;a href="#cb22-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
417&lt;span id="cb22-7"&gt;&lt;a href="#cb22-7"&gt;&lt;/a&gt;&lt;/span&gt; 545&lt;span id="cb22-7"&gt;&lt;a href="#cb22-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
418&lt;span id="cb22-8"&gt;&lt;a href="#cb22-8"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;test&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt; 546&lt;span id="cb22-8"&gt;&lt;a href="#cb22-8" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;test&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt;
419&lt;span id="cb22-9"&gt;&lt;a href="#cb22-9"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; works() &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 547&lt;span id="cb22-9"&gt;&lt;a href="#cb22-9" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; works() &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
420&lt;span id="cb22-10"&gt;&lt;a href="#cb22-10"&gt;&lt;/a&gt; &lt;span class="pp"&gt;assert!&lt;/span&gt;(&lt;span class="cn"&gt;true&lt;/span&gt;);&lt;/span&gt; 548&lt;span id="cb22-10"&gt;&lt;a href="#cb22-10" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="pp"&gt;assert!&lt;/span&gt;(&lt;span class="cn"&gt;true&lt;/span&gt;)&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
421&lt;span id="cb22-11"&gt;&lt;a href="#cb22-11"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 549&lt;span id="cb22-11"&gt;&lt;a href="#cb22-11" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
422&lt;p&gt;You should find something like this in the output of &lt;code&gt;cargo test&lt;/code&gt;:&lt;/p&gt; 550&lt;p&gt;You should find something like this in the output of &lt;code&gt;cargo test&lt;/code&gt;:&lt;/p&gt;
423&lt;pre&gt;&lt;code&gt;return move | y | move | z | { x + y + z }&lt;/code&gt;&lt;/pre&gt; 551&lt;pre&gt;&lt;code&gt;return move | y | move | z | { x + y + z }&lt;/code&gt;&lt;/pre&gt;
424&lt;p&gt;Glorious &lt;code&gt;println!&lt;/code&gt; debugging!&lt;/p&gt; 552&lt;p&gt;Glorious &lt;code&gt;println!&lt;/code&gt; debugging!&lt;/p&gt;
425&lt;h4 id="function-signature"&gt;Function signature&lt;/h4&gt; 553&lt;h4 id="function-signature"&gt;Function signature&lt;/h4&gt;
426&lt;p&gt;This section gets into the more complicated bits of the macro, generating type aliases and the function signature. By the end of this section, we should have a full working auto-currying macro!&lt;/p&gt; 554&lt;p&gt;This section gets into the more complicated bits of the macro, generating type aliases and the function signature. By the end of this section, we should have a full working auto-currying macro!&lt;/p&gt;
427&lt;p&gt;Recall what our generated type aliases should look like, for our &lt;code&gt;add&lt;/code&gt; function:&lt;/p&gt; 555&lt;p&gt;Recall what our generated type aliases should look like, for our &lt;code&gt;add&lt;/code&gt; function:&lt;/p&gt;
428&lt;div class="sourceCode" id="cb24"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb24-1"&gt;&lt;a href="#cb24-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 = &lt;span class="dt"&gt;u32&lt;/span&gt;;&lt;/span&gt; 556&lt;div class="sourceCode" id="cb24"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb24-1"&gt;&lt;a href="#cb24-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
429&lt;span id="cb24-2"&gt;&lt;a href="#cb24-2"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T1 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; T0;&lt;/span&gt; 557&lt;span id="cb24-2"&gt;&lt;a href="#cb24-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T1 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; T0&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
430&lt;span id="cb24-3"&gt;&lt;a href="#cb24-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T2 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; T1;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 558&lt;span id="cb24-3"&gt;&lt;a href="#cb24-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T2 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; T1&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
431&lt;p&gt;In general:&lt;/p&gt; 559&lt;p&gt;In general:&lt;/p&gt;
432&lt;div class="sourceCode" id="cb25"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb25-1"&gt;&lt;a href="#cb25-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 = &amp;lt;&lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;type&lt;/span&gt;&amp;gt;;&lt;/span&gt; 560&lt;div class="sourceCode" id="cb25"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb25-1"&gt;&lt;a href="#cb25-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="kw"&gt;type&lt;/span&gt;&amp;gt;&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
433&lt;span id="cb25-2"&gt;&lt;a href="#cb25-2"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T1 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&amp;lt;&lt;span class="kw"&gt;type&lt;/span&gt; of arg N&amp;gt;) -&amp;gt; T0;&lt;/span&gt; 561&lt;span id="cb25-2"&gt;&lt;a href="#cb25-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T1 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="kw"&gt;type&lt;/span&gt; of arg N&amp;gt;) -&amp;gt; T0&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
434&lt;span id="cb25-3"&gt;&lt;a href="#cb25-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T2 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&amp;lt;&lt;span class="kw"&gt;type&lt;/span&gt; of arg N - 1&amp;gt;) -&amp;gt; T1;&lt;/span&gt; 562&lt;span id="cb25-3"&gt;&lt;a href="#cb25-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T2 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="kw"&gt;type&lt;/span&gt; of arg N - 1&amp;gt;) -&amp;gt; T1&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
435&lt;span id="cb25-4"&gt;&lt;a href="#cb25-4"&gt;&lt;/a&gt;.&lt;/span&gt; 563&lt;span id="cb25-4"&gt;&lt;a href="#cb25-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;.&lt;/span&gt;&lt;/span&gt;
436&lt;span id="cb25-5"&gt;&lt;a href="#cb25-5"&gt;&lt;/a&gt;.&lt;/span&gt; 564&lt;span id="cb25-5"&gt;&lt;a href="#cb25-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;.&lt;/span&gt;&lt;/span&gt;
437&lt;span id="cb25-6"&gt;&lt;a href="#cb25-6"&gt;&lt;/a&gt;.&lt;/span&gt; 565&lt;span id="cb25-6"&gt;&lt;a href="#cb25-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;.&lt;/span&gt;&lt;/span&gt;
438&lt;span id="cb25-7"&gt;&lt;a href="#cb25-7"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T(N-1) = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&amp;lt;&lt;span class="kw"&gt;type&lt;/span&gt; of arg 2&amp;gt;) -&amp;gt; T(N-2);&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 566&lt;span id="cb25-7"&gt;&lt;a href="#cb25-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T(N-1) &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="kw"&gt;type&lt;/span&gt; of arg 2&amp;gt;) -&amp;gt; T(N-2)&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
439&lt;p&gt;To codegen that, we need the types of:&lt;/p&gt; 567&lt;p&gt;To codegen that, we need the types of:&lt;/p&gt;
440&lt;ul&gt; 568&lt;ul&gt;
441&lt;li&gt;all our inputs (arguments)&lt;/li&gt; 569&lt;li&gt;all our inputs (arguments)&lt;/li&gt;
442&lt;li&gt;the output (the return type)&lt;/li&gt; 570&lt;li&gt;the output (the return type)&lt;/li&gt;
443&lt;/ul&gt; 571&lt;/ul&gt;
444&lt;p&gt;To fetch the types of all our inputs, we can simply reuse the bits we wrote to fetch the names of all our inputs! (doc: &lt;a href="https://docs.rs/syn/1.0.18/syn/enum.Type.html"&gt;Type&lt;/a&gt;)&lt;/p&gt; 572&lt;p&gt;To fetch the types of all our inputs, we can simply reuse the bits we wrote to fetch the names of all our inputs! (doc: &lt;a href="https://docs.rs/syn/1.0.18/syn/enum.Type.html"&gt;Type&lt;/a&gt;)&lt;/p&gt;
445&lt;div class="sourceCode" id="cb26"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb26-1"&gt;&lt;a href="#cb26-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt; 573&lt;div class="sourceCode" id="cb26"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb26-1"&gt;&lt;a href="#cb26-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt;
446&lt;span id="cb26-2"&gt;&lt;a href="#cb26-2"&gt;&lt;/a&gt;&lt;/span&gt; 574&lt;span id="cb26-2"&gt;&lt;a href="#cb26-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
447&lt;span id="cb26-3"&gt;&lt;a href="#cb26-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;syn::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;parse_macro_input, Block, FnArg, ItemFn, Pat, ReturnType, Type&lt;span class="op"&gt;}&lt;/span&gt;;&lt;/span&gt; 575&lt;span id="cb26-3"&gt;&lt;a href="#cb26-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;syn::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;parse_macro_input&lt;span class="op"&gt;,&lt;/span&gt; Block&lt;span class="op"&gt;,&lt;/span&gt; FnArg&lt;span class="op"&gt;,&lt;/span&gt; ItemFn&lt;span class="op"&gt;,&lt;/span&gt; Pat&lt;span class="op"&gt;,&lt;/span&gt; ReturnType&lt;span class="op"&gt;,&lt;/span&gt; Type&lt;span class="op"&gt;};&lt;/span&gt;&lt;/span&gt;
448&lt;span id="cb26-4"&gt;&lt;a href="#cb26-4"&gt;&lt;/a&gt;&lt;/span&gt; 576&lt;span id="cb26-4"&gt;&lt;a href="#cb26-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
449&lt;span id="cb26-5"&gt;&lt;a href="#cb26-5"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; extract_type(a: FnArg) -&amp;gt; &lt;span class="dt"&gt;Box&lt;/span&gt;&amp;lt;Type&amp;gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 577&lt;span id="cb26-5"&gt;&lt;a href="#cb26-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; extract_type(a&lt;span class="op"&gt;:&lt;/span&gt; FnArg) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;Box&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;Type&lt;span class="op"&gt;&amp;gt;&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
450&lt;span id="cb26-6"&gt;&lt;a href="#cb26-6"&gt;&lt;/a&gt; &lt;span class="kw"&gt;match&lt;/span&gt; a &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 578&lt;span id="cb26-6"&gt;&lt;a href="#cb26-6" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;match&lt;/span&gt; a &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
451&lt;span id="cb26-7"&gt;&lt;a href="#cb26-7"&gt;&lt;/a&gt; &lt;span class="pp"&gt;FnArg::&lt;/span&gt;Typed(p) =&amp;gt; p.ty, &lt;span class="co"&gt;// notice `ty` instead of `pat`&lt;/span&gt;&lt;/span&gt; 579&lt;span id="cb26-7"&gt;&lt;a href="#cb26-7" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="pp"&gt;FnArg::&lt;/span&gt;Typed(p) &lt;span class="op"&gt;=&amp;gt;&lt;/span&gt; p&lt;span class="op"&gt;.&lt;/span&gt;ty&lt;span class="op"&gt;,&lt;/span&gt; &lt;span class="co"&gt;// notice `ty` instead of `pat`&lt;/span&gt;&lt;/span&gt;
452&lt;span id="cb26-8"&gt;&lt;a href="#cb26-8"&gt;&lt;/a&gt; _ =&amp;gt; &lt;span class="pp"&gt;panic!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;Not supported on types with `self`!&amp;quot;&lt;/span&gt;),&lt;/span&gt; 580&lt;span id="cb26-8"&gt;&lt;a href="#cb26-8" aria-hidden="true"&gt;&lt;/a&gt; _ &lt;span class="op"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="pp"&gt;panic!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;Not supported on types with `self`!&amp;quot;&lt;/span&gt;)&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
453&lt;span id="cb26-9"&gt;&lt;a href="#cb26-9"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 581&lt;span id="cb26-9"&gt;&lt;a href="#cb26-9" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
454&lt;span id="cb26-10"&gt;&lt;a href="#cb26-10"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 582&lt;span id="cb26-10"&gt;&lt;a href="#cb26-10" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
455&lt;span id="cb26-11"&gt;&lt;a href="#cb26-11"&gt;&lt;/a&gt;&lt;/span&gt; 583&lt;span id="cb26-11"&gt;&lt;a href="#cb26-11" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
456&lt;span id="cb26-12"&gt;&lt;a href="#cb26-12"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; extract_arg_types(fn_args: Punctuated&amp;lt;FnArg, &lt;span class="pp"&gt;syn::token::&lt;/span&gt;Comma&amp;gt;) -&amp;gt; &lt;span class="dt"&gt;Vec&lt;/span&gt;&amp;lt;&lt;span class="dt"&gt;Box&lt;/span&gt;&amp;lt;Type&amp;gt;&amp;gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 584&lt;span id="cb26-12"&gt;&lt;a href="#cb26-12" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; extract_arg_types(fn_args&lt;span class="op"&gt;:&lt;/span&gt; Punctuated&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;FnArg&lt;span class="op"&gt;,&lt;/span&gt; &lt;span class="pp"&gt;syn::token::&lt;/span&gt;Comma&lt;span class="op"&gt;&amp;gt;&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;Vec&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="dt"&gt;Box&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;Type&lt;span class="op"&gt;&amp;gt;&amp;gt;&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
457&lt;span id="cb26-13"&gt;&lt;a href="#cb26-13"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; fn_args.into_iter().map(extract_type).&lt;span class="pp"&gt;collect::&lt;/span&gt;&amp;lt;&lt;span class="dt"&gt;Vec&lt;/span&gt;&amp;lt;_&amp;gt;&amp;gt;();&lt;/span&gt; 585&lt;span id="cb26-13"&gt;&lt;a href="#cb26-13" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; fn_args&lt;span class="op"&gt;.&lt;/span&gt;into_iter()&lt;span class="op"&gt;.&lt;/span&gt;map(extract_type)&lt;span class="op"&gt;.&lt;/span&gt;&lt;span class="pp"&gt;collect::&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="dt"&gt;Vec&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;_&lt;span class="op"&gt;&amp;gt;&amp;gt;&lt;/span&gt;()&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
458&lt;span id="cb26-14"&gt;&lt;a href="#cb26-14"&gt;&lt;/a&gt;&lt;/span&gt; 586&lt;span id="cb26-14"&gt;&lt;a href="#cb26-14" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
459&lt;span id="cb26-15"&gt;&lt;a href="#cb26-15"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 587&lt;span id="cb26-15"&gt;&lt;a href="#cb26-15" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
460&lt;p&gt;A good reader would have looked at the docs for output member of the &lt;code&gt;syn::Signature&lt;/code&gt; struct. It has the type &lt;code&gt;syn::ReturnType&lt;/code&gt;. So there is no extraction to do here right? There are actually a couple of things we have to ensure here:&lt;/p&gt; 588&lt;p&gt;A good reader would have looked at the docs for output member of the &lt;code&gt;syn::Signature&lt;/code&gt; struct. It has the type &lt;code&gt;syn::ReturnType&lt;/code&gt;. So there is no extraction to do here right? There are actually a couple of things we have to ensure here:&lt;/p&gt;
461&lt;ol type="1"&gt; 589&lt;ol type="1"&gt;
462&lt;li&gt;&lt;p&gt;We need to ensure that the function returns! A function that does not return is pointless in this case, and I will tell you why, in the &lt;a href="#notes"&gt;Notes&lt;/a&gt; section.&lt;/p&gt;&lt;/li&gt; 590&lt;li&gt;&lt;p&gt;We need to ensure that the function returns! A function that does not return is pointless in this case, and I will tell you why, in the &lt;a href="#notes"&gt;Notes&lt;/a&gt; section.&lt;/p&gt;&lt;/li&gt;
463&lt;li&gt;&lt;p&gt;A &lt;code&gt;ReturnType&lt;/code&gt; encloses the arrow of the return as well, we need to get rid of that. Recall:&lt;/p&gt; 591&lt;li&gt;&lt;p&gt;A &lt;code&gt;ReturnType&lt;/code&gt; encloses the arrow of the return as well, we need to get rid of that. Recall:&lt;/p&gt;
464&lt;div class="sourceCode" id="cb27"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb27-1"&gt;&lt;a href="#cb27-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 = &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;/span&gt; 592&lt;div class="sourceCode" id="cb27"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb27-1"&gt;&lt;a href="#cb27-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;/span&gt;
465&lt;span id="cb27-2"&gt;&lt;a href="#cb27-2"&gt;&lt;/a&gt;&lt;span class="co"&gt;// and not&lt;/span&gt;&lt;/span&gt; 593&lt;span id="cb27-2"&gt;&lt;a href="#cb27-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// and not&lt;/span&gt;&lt;/span&gt;
466&lt;span id="cb27-3"&gt;&lt;a href="#cb27-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 = -&amp;gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;&lt;/li&gt; 594&lt;span id="cb27-3"&gt;&lt;a href="#cb27-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;&lt;/li&gt;
467&lt;/ol&gt; 595&lt;/ol&gt;
468&lt;p&gt;Here is the snippet that handles extraction of the return type (doc: &lt;a href="https://docs.rs/syn/1.0.19/syn/enum.ReturnType.html"&gt;syn::ReturnType&lt;/a&gt;):&lt;/p&gt; 596&lt;p&gt;Here is the snippet that handles extraction of the return type (doc: &lt;a href="https://docs.rs/syn/1.0.19/syn/enum.ReturnType.html"&gt;syn::ReturnType&lt;/a&gt;):&lt;/p&gt;
469&lt;div class="sourceCode" id="cb28"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb28-1"&gt;&lt;a href="#cb28-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt; 597&lt;div class="sourceCode" id="cb28"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb28-1"&gt;&lt;a href="#cb28-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt;
470&lt;span id="cb28-2"&gt;&lt;a href="#cb28-2"&gt;&lt;/a&gt;&lt;/span&gt; 598&lt;span id="cb28-2"&gt;&lt;a href="#cb28-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
471&lt;span id="cb28-3"&gt;&lt;a href="#cb28-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; extract_return_type(a: ReturnType) -&amp;gt; &lt;span class="dt"&gt;Box&lt;/span&gt;&amp;lt;Type&amp;gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 599&lt;span id="cb28-3"&gt;&lt;a href="#cb28-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; extract_return_type(a&lt;span class="op"&gt;:&lt;/span&gt; ReturnType) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;Box&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;Type&lt;span class="op"&gt;&amp;gt;&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
472&lt;span id="cb28-4"&gt;&lt;a href="#cb28-4"&gt;&lt;/a&gt; &lt;span class="kw"&gt;match&lt;/span&gt; a &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 600&lt;span id="cb28-4"&gt;&lt;a href="#cb28-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;match&lt;/span&gt; a &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
473&lt;span id="cb28-5"&gt;&lt;a href="#cb28-5"&gt;&lt;/a&gt; &lt;span class="pp"&gt;ReturnType::&lt;/span&gt;Type(_, p) =&amp;gt; p,&lt;/span&gt; 601&lt;span id="cb28-5"&gt;&lt;a href="#cb28-5" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="pp"&gt;ReturnType::&lt;/span&gt;Type(_&lt;span class="op"&gt;,&lt;/span&gt; p) &lt;span class="op"&gt;=&amp;gt;&lt;/span&gt; p&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
474&lt;span id="cb28-6"&gt;&lt;a href="#cb28-6"&gt;&lt;/a&gt; _ =&amp;gt; &lt;span class="pp"&gt;panic!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;Not supported on functions without return types!&amp;quot;&lt;/span&gt;),&lt;/span&gt; 602&lt;span id="cb28-6"&gt;&lt;a href="#cb28-6" aria-hidden="true"&gt;&lt;/a&gt; _ &lt;span class="op"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="pp"&gt;panic!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;Not supported on functions without return types!&amp;quot;&lt;/span&gt;)&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
475&lt;span id="cb28-7"&gt;&lt;a href="#cb28-7"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 603&lt;span id="cb28-7"&gt;&lt;a href="#cb28-7" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
476&lt;span id="cb28-8"&gt;&lt;a href="#cb28-8"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 604&lt;span id="cb28-8"&gt;&lt;a href="#cb28-8" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
477&lt;p&gt;You might notice that we are making extensive use of the &lt;code&gt;panic!&lt;/code&gt; macro. Well, that is because it is a good idea to quit on receiving an unsatisfactory &lt;code&gt;TokenStream&lt;/code&gt;.&lt;/p&gt; 605&lt;p&gt;You might notice that we are making extensive use of the &lt;code&gt;panic!&lt;/code&gt; macro. Well, that is because it is a good idea to quit on receiving an unsatisfactory &lt;code&gt;TokenStream&lt;/code&gt;.&lt;/p&gt;
478&lt;p&gt;With all our types ready, we can get on with generating type aliases:&lt;/p&gt; 606&lt;p&gt;With all our types ready, we can get on with generating type aliases:&lt;/p&gt;
479&lt;div class="sourceCode" id="cb29"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb29-1"&gt;&lt;a href="#cb29-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt; 607&lt;div class="sourceCode" id="cb29"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb29-1"&gt;&lt;a href="#cb29-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt;
480&lt;span id="cb29-2"&gt;&lt;a href="#cb29-2"&gt;&lt;/a&gt;&lt;/span&gt; 608&lt;span id="cb29-2"&gt;&lt;a href="#cb29-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
481&lt;span id="cb29-3"&gt;&lt;a href="#cb29-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;quote::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;quote, format_ident&lt;span class="op"&gt;}&lt;/span&gt;;&lt;/span&gt; 609&lt;span id="cb29-3"&gt;&lt;a href="#cb29-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;quote::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;quote&lt;span class="op"&gt;,&lt;/span&gt; format_ident&lt;span class="op"&gt;};&lt;/span&gt;&lt;/span&gt;
482&lt;span id="cb29-4"&gt;&lt;a href="#cb29-4"&gt;&lt;/a&gt;&lt;/span&gt; 610&lt;span id="cb29-4"&gt;&lt;a href="#cb29-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
483&lt;span id="cb29-5"&gt;&lt;a href="#cb29-5"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; generate_type_aliases(&lt;/span&gt; 611&lt;span id="cb29-5"&gt;&lt;a href="#cb29-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; generate_type_aliases(&lt;/span&gt;
484&lt;span id="cb29-6"&gt;&lt;a href="#cb29-6"&gt;&lt;/a&gt; fn_arg_types: &amp;amp;&lt;span class="op"&gt;[&lt;/span&gt;&lt;span class="dt"&gt;Box&lt;/span&gt;&amp;lt;Type&amp;gt;&lt;span class="op"&gt;]&lt;/span&gt;,&lt;/span&gt; 612&lt;span id="cb29-6"&gt;&lt;a href="#cb29-6" aria-hidden="true"&gt;&lt;/a&gt; fn_arg_types&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="op"&gt;&amp;amp;&lt;/span&gt;[&lt;span class="dt"&gt;Box&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;Type&lt;span class="op"&gt;&amp;gt;&lt;/span&gt;]&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
485&lt;span id="cb29-7"&gt;&lt;a href="#cb29-7"&gt;&lt;/a&gt; fn_return_type: &lt;span class="dt"&gt;Box&lt;/span&gt;&amp;lt;Type&amp;gt;,&lt;/span&gt; 613&lt;span id="cb29-7"&gt;&lt;a href="#cb29-7" aria-hidden="true"&gt;&lt;/a&gt; fn_return_type&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;Box&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;Type&lt;span class="op"&gt;&amp;gt;,&lt;/span&gt;&lt;/span&gt;
486&lt;span id="cb29-8"&gt;&lt;a href="#cb29-8"&gt;&lt;/a&gt; fn_name: &amp;amp;&lt;span class="pp"&gt;syn::&lt;/span&gt;Ident,&lt;/span&gt; 614&lt;span id="cb29-8"&gt;&lt;a href="#cb29-8" aria-hidden="true"&gt;&lt;/a&gt; fn_name&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="op"&gt;&amp;amp;&lt;/span&gt;&lt;span class="pp"&gt;syn::&lt;/span&gt;Ident&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
487&lt;span id="cb29-9"&gt;&lt;a href="#cb29-9"&gt;&lt;/a&gt;) -&amp;gt; &lt;span class="dt"&gt;Vec&lt;/span&gt;&amp;lt;&lt;span class="pp"&gt;proc_macro2::&lt;/span&gt;TokenStream&amp;gt; &lt;span class="op"&gt;{&lt;/span&gt; &lt;span class="co"&gt;// 1&lt;/span&gt;&lt;/span&gt; 615&lt;span id="cb29-9"&gt;&lt;a href="#cb29-9" aria-hidden="true"&gt;&lt;/a&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;Vec&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="pp"&gt;proc_macro2::&lt;/span&gt;TokenStream&lt;span class="op"&gt;&amp;gt;&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt; &lt;span class="co"&gt;// 1&lt;/span&gt;&lt;/span&gt;
488&lt;span id="cb29-10"&gt;&lt;a href="#cb29-10"&gt;&lt;/a&gt;&lt;/span&gt; 616&lt;span id="cb29-10"&gt;&lt;a href="#cb29-10" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
489&lt;span id="cb29-11"&gt;&lt;a href="#cb29-11"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; type_t0 = &lt;span class="pp"&gt;format_ident!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;_{}_T0&amp;quot;&lt;/span&gt;, fn_name); &lt;span class="co"&gt;// 2&lt;/span&gt;&lt;/span&gt; 617&lt;span id="cb29-11"&gt;&lt;a href="#cb29-11" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; type_t0 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="pp"&gt;format_ident!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;_{}_T0&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; fn_name)&lt;span class="op"&gt;;&lt;/span&gt; &lt;span class="co"&gt;// 2&lt;/span&gt;&lt;/span&gt;
490&lt;span id="cb29-12"&gt;&lt;a href="#cb29-12"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; &lt;span class="kw"&gt;mut&lt;/span&gt; type_aliases = &lt;span class="pp"&gt;vec!&lt;/span&gt;&lt;span class="op"&gt;[&lt;/span&gt;&lt;span class="pp"&gt;quote!&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt; &lt;span class="kw"&gt;type&lt;/span&gt; #type_t0 = #fn_return_type &lt;span class="op"&gt;}]&lt;/span&gt;;&lt;/span&gt; 618&lt;span id="cb29-12"&gt;&lt;a href="#cb29-12" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; &lt;span class="kw"&gt;mut&lt;/span&gt; type_aliases &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="pp"&gt;vec!&lt;/span&gt;[&lt;span class="pp"&gt;quote!&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt; &lt;span class="kw"&gt;type&lt;/span&gt; #type_t0 &lt;span class="op"&gt;=&lt;/span&gt; #fn_return_type &lt;span class="op"&gt;}&lt;/span&gt;]&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
491&lt;span id="cb29-13"&gt;&lt;a href="#cb29-13"&gt;&lt;/a&gt;&lt;/span&gt; 619&lt;span id="cb29-13"&gt;&lt;a href="#cb29-13" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
492&lt;span id="cb29-14"&gt;&lt;a href="#cb29-14"&gt;&lt;/a&gt; &lt;span class="co"&gt;// 3&lt;/span&gt;&lt;/span&gt; 620&lt;span id="cb29-14"&gt;&lt;a href="#cb29-14" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="co"&gt;// 3&lt;/span&gt;&lt;/span&gt;
493&lt;span id="cb29-15"&gt;&lt;a href="#cb29-15"&gt;&lt;/a&gt; &lt;span class="kw"&gt;for&lt;/span&gt; (i, t) &lt;span class="kw"&gt;in&lt;/span&gt; (&lt;span class="dv"&gt;1&lt;/span&gt;..).zip(fn_arg_types.into_iter().rev()) &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 621&lt;span id="cb29-15"&gt;&lt;a href="#cb29-15" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;for&lt;/span&gt; (i&lt;span class="op"&gt;,&lt;/span&gt; t) &lt;span class="kw"&gt;in&lt;/span&gt; (&lt;span class="dv"&gt;1&lt;/span&gt;&lt;span class="op"&gt;..&lt;/span&gt;)&lt;span class="op"&gt;.&lt;/span&gt;zip(fn_arg_types&lt;span class="op"&gt;.&lt;/span&gt;into_iter()&lt;span class="op"&gt;.&lt;/span&gt;rev()) &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
494&lt;span id="cb29-16"&gt;&lt;a href="#cb29-16"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; p = &lt;span class="pp"&gt;format_ident!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;_{}_{}&amp;quot;&lt;/span&gt;, fn_name, &lt;span class="pp"&gt;format!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;T{}&amp;quot;&lt;/span&gt;, i - &lt;span class="dv"&gt;1&lt;/span&gt;));&lt;/span&gt; 622&lt;span id="cb29-16"&gt;&lt;a href="#cb29-16" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; p &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="pp"&gt;format_ident!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;_{}_{}&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; fn_name&lt;span class="op"&gt;,&lt;/span&gt; &lt;span class="pp"&gt;format!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;T{}&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; i &lt;span class="op"&gt;-&lt;/span&gt; &lt;span class="dv"&gt;1&lt;/span&gt;))&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
495&lt;span id="cb29-17"&gt;&lt;a href="#cb29-17"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; n = &lt;span class="pp"&gt;format_ident!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;_{}_{}&amp;quot;&lt;/span&gt;, fn_name, &lt;span class="pp"&gt;format!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;T{}&amp;quot;&lt;/span&gt;, i));&lt;/span&gt; 623&lt;span id="cb29-17"&gt;&lt;a href="#cb29-17" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; n &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="pp"&gt;format_ident!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;_{}_{}&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; fn_name&lt;span class="op"&gt;,&lt;/span&gt; &lt;span class="pp"&gt;format!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;T{}&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; i))&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
496&lt;span id="cb29-18"&gt;&lt;a href="#cb29-18"&gt;&lt;/a&gt;&lt;/span&gt; 624&lt;span id="cb29-18"&gt;&lt;a href="#cb29-18" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
497&lt;span id="cb29-19"&gt;&lt;a href="#cb29-19"&gt;&lt;/a&gt; type_aliases.push(&lt;span class="pp"&gt;quote!&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 625&lt;span id="cb29-19"&gt;&lt;a href="#cb29-19" aria-hidden="true"&gt;&lt;/a&gt; type_aliases&lt;span class="op"&gt;.&lt;/span&gt;push(&lt;span class="pp"&gt;quote!&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
498&lt;span id="cb29-20"&gt;&lt;a href="#cb29-20"&gt;&lt;/a&gt; &lt;span class="kw"&gt;type&lt;/span&gt; #n = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(#t) -&amp;gt; #p&lt;/span&gt; 626&lt;span id="cb29-20"&gt;&lt;a href="#cb29-20" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;type&lt;/span&gt; #n &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(#t) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; #p&lt;/span&gt;
499&lt;span id="cb29-21"&gt;&lt;a href="#cb29-21"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;);&lt;/span&gt; 627&lt;span id="cb29-21"&gt;&lt;a href="#cb29-21" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;)&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
500&lt;span id="cb29-22"&gt;&lt;a href="#cb29-22"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 628&lt;span id="cb29-22"&gt;&lt;a href="#cb29-22" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
501&lt;span id="cb29-23"&gt;&lt;a href="#cb29-23"&gt;&lt;/a&gt;&lt;/span&gt; 629&lt;span id="cb29-23"&gt;&lt;a href="#cb29-23" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
502&lt;span id="cb29-24"&gt;&lt;a href="#cb29-24"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; type_aliases;&lt;/span&gt; 630&lt;span id="cb29-24"&gt;&lt;a href="#cb29-24" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; type_aliases&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
503&lt;span id="cb29-25"&gt;&lt;a href="#cb29-25"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 631&lt;span id="cb29-25"&gt;&lt;a href="#cb29-25" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
504&lt;p&gt;&lt;strong&gt;1. The return value&lt;/strong&gt;&lt;br /&gt; 632&lt;p&gt;&lt;strong&gt;1. The return value&lt;/strong&gt;&lt;br /&gt;
505We are returning a &lt;code&gt;Vec&amp;lt;proc_macro2::TokenStream&amp;gt;&lt;/code&gt;, i. e., a list of &lt;code&gt;TokenStream&lt;/code&gt;s, where each item is a type alias.&lt;/p&gt; 633We are returning a &lt;code&gt;Vec&amp;lt;proc_macro2::TokenStream&amp;gt;&lt;/code&gt;, i. e., a list of &lt;code&gt;TokenStream&lt;/code&gt;s, where each item is a type alias.&lt;/p&gt;
506&lt;p&gt;&lt;strong&gt;2. Format identifier?&lt;/strong&gt;&lt;br /&gt; 634&lt;p&gt;&lt;strong&gt;2. Format identifier?&lt;/strong&gt;&lt;br /&gt;
507I’ve got some explanation to do on this line. Clearly, we are trying to write the first type alias, and initialize our &lt;code&gt;TokenStream&lt;/code&gt; vector with &lt;code&gt;T0&lt;/code&gt;, because it is different from the others:&lt;/p&gt; 635I’ve got some explanation to do on this line. Clearly, we are trying to write the first type alias, and initialize our &lt;code&gt;TokenStream&lt;/code&gt; vector with &lt;code&gt;T0&lt;/code&gt;, because it is different from the others:&lt;/p&gt;
508&lt;div class="sourceCode" id="cb30"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb30-1"&gt;&lt;a href="#cb30-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 = something&lt;/span&gt; 636&lt;div class="sourceCode" id="cb30"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb30-1"&gt;&lt;a href="#cb30-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 &lt;span class="op"&gt;=&lt;/span&gt; something&lt;/span&gt;
509&lt;span id="cb30-2"&gt;&lt;a href="#cb30-2"&gt;&lt;/a&gt;&lt;span class="co"&gt;// the others are of the form&lt;/span&gt;&lt;/span&gt; 637&lt;span id="cb30-2"&gt;&lt;a href="#cb30-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// the others are of the form&lt;/span&gt;&lt;/span&gt;
510&lt;span id="cb30-3"&gt;&lt;a href="#cb30-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; Tr = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(something) -&amp;gt; something&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 638&lt;span id="cb30-3"&gt;&lt;a href="#cb30-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; Tr &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(something) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; something&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
511&lt;p&gt;&lt;code&gt;format_ident!&lt;/code&gt; is similar to &lt;code&gt;format!&lt;/code&gt;. Instead of returning a formatted string, it returns a &lt;code&gt;syn::Ident&lt;/code&gt;. Therefore, &lt;code&gt;type_t0&lt;/code&gt; is actually an identifier for, in the case of our &lt;code&gt;add&lt;/code&gt; function, &lt;code&gt;_add_T0&lt;/code&gt;. Why is this formatting important? Namespacing.&lt;/p&gt; 639&lt;p&gt;&lt;code&gt;format_ident!&lt;/code&gt; is similar to &lt;code&gt;format!&lt;/code&gt;. Instead of returning a formatted string, it returns a &lt;code&gt;syn::Ident&lt;/code&gt;. Therefore, &lt;code&gt;type_t0&lt;/code&gt; is actually an identifier for, in the case of our &lt;code&gt;add&lt;/code&gt; function, &lt;code&gt;_add_T0&lt;/code&gt;. Why is this formatting important? Namespacing.&lt;/p&gt;
512&lt;p&gt;Picture this, we have two functions, &lt;code&gt;add&lt;/code&gt; and &lt;code&gt;subtract&lt;/code&gt;, that we wish to curry with our macro:&lt;/p&gt; 640&lt;p&gt;Picture this, we have two functions, &lt;code&gt;add&lt;/code&gt; and &lt;code&gt;subtract&lt;/code&gt;, that we wish to curry with our macro:&lt;/p&gt;
513&lt;div class="sourceCode" id="cb31"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb31-1"&gt;&lt;a href="#cb31-1"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;curry&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt; 641&lt;div class="sourceCode" id="cb31"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb31-1"&gt;&lt;a href="#cb31-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;curry&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt;
514&lt;span id="cb31-2"&gt;&lt;a href="#cb31-2"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(...) -&amp;gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt; ... &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 642&lt;span id="cb31-2"&gt;&lt;a href="#cb31-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(&lt;span class="op"&gt;...&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt; &lt;span class="op"&gt;...&lt;/span&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
515&lt;span id="cb31-3"&gt;&lt;a href="#cb31-3"&gt;&lt;/a&gt;&lt;/span&gt; 643&lt;span id="cb31-3"&gt;&lt;a href="#cb31-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
516&lt;span id="cb31-4"&gt;&lt;a href="#cb31-4"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;curry&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt; 644&lt;span id="cb31-4"&gt;&lt;a href="#cb31-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;curry&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt;
517&lt;span id="cb31-5"&gt;&lt;a href="#cb31-5"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; sub(...) -&amp;gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt; ... &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 645&lt;span id="cb31-5"&gt;&lt;a href="#cb31-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; sub(&lt;span class="op"&gt;...&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt; &lt;span class="op"&gt;...&lt;/span&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
518&lt;p&gt;Here is the same but with macros expanded:&lt;/p&gt; 646&lt;p&gt;Here is the same but with macros expanded:&lt;/p&gt;
519&lt;div class="sourceCode" id="cb32"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb32-1"&gt;&lt;a href="#cb32-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 = &lt;span class="dt"&gt;u32&lt;/span&gt;;&lt;/span&gt; 647&lt;div class="sourceCode" id="cb32"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb32-1"&gt;&lt;a href="#cb32-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
520&lt;span id="cb32-2"&gt;&lt;a href="#cb32-2"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T1 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; T0;&lt;/span&gt; 648&lt;span id="cb32-2"&gt;&lt;a href="#cb32-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T1 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; T0&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
521&lt;span id="cb32-3"&gt;&lt;a href="#cb32-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add( ... ) -&amp;gt; T1 &lt;span class="op"&gt;{&lt;/span&gt; ... &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 649&lt;span id="cb32-3"&gt;&lt;a href="#cb32-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add( &lt;span class="op"&gt;...&lt;/span&gt; ) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; T1 &lt;span class="op"&gt;{&lt;/span&gt; &lt;span class="op"&gt;...&lt;/span&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
522&lt;span id="cb32-4"&gt;&lt;a href="#cb32-4"&gt;&lt;/a&gt;&lt;/span&gt; 650&lt;span id="cb32-4"&gt;&lt;a href="#cb32-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
523&lt;span id="cb32-5"&gt;&lt;a href="#cb32-5"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 = &lt;span class="dt"&gt;u32&lt;/span&gt;;&lt;/span&gt; 651&lt;span id="cb32-5"&gt;&lt;a href="#cb32-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T0 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
524&lt;span id="cb32-6"&gt;&lt;a href="#cb32-6"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T1 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; T0;&lt;/span&gt; 652&lt;span id="cb32-6"&gt;&lt;a href="#cb32-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; T1 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; T0&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
525&lt;span id="cb32-7"&gt;&lt;a href="#cb32-7"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; sub( ... ) -&amp;gt; T1 &lt;span class="op"&gt;{&lt;/span&gt; ... &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 653&lt;span id="cb32-7"&gt;&lt;a href="#cb32-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; sub( &lt;span class="op"&gt;...&lt;/span&gt; ) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; T1 &lt;span class="op"&gt;{&lt;/span&gt; &lt;span class="op"&gt;...&lt;/span&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
526&lt;p&gt;We end up with two definitions of &lt;code&gt;T0&lt;/code&gt;! Now, if we do the little &lt;code&gt;format_ident!&lt;/code&gt; dance we did up there:&lt;/p&gt; 654&lt;p&gt;We end up with two definitions of &lt;code&gt;T0&lt;/code&gt;! Now, if we do the little &lt;code&gt;format_ident!&lt;/code&gt; dance we did up there:&lt;/p&gt;
527&lt;div class="sourceCode" id="cb33"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb33-1"&gt;&lt;a href="#cb33-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _add_T0 = &lt;span class="dt"&gt;u32&lt;/span&gt;;&lt;/span&gt; 655&lt;div class="sourceCode" id="cb33"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb33-1"&gt;&lt;a href="#cb33-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _add_T0 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
528&lt;span id="cb33-2"&gt;&lt;a href="#cb33-2"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _add_T1 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; _add_T0;&lt;/span&gt; 656&lt;span id="cb33-2"&gt;&lt;a href="#cb33-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _add_T1 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; _add_T0&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
529&lt;span id="cb33-3"&gt;&lt;a href="#cb33-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add( ... ) -&amp;gt; _add_T1 &lt;span class="op"&gt;{&lt;/span&gt; ... &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 657&lt;span id="cb33-3"&gt;&lt;a href="#cb33-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add( &lt;span class="op"&gt;...&lt;/span&gt; ) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; _add_T1 &lt;span class="op"&gt;{&lt;/span&gt; &lt;span class="op"&gt;...&lt;/span&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
530&lt;span id="cb33-4"&gt;&lt;a href="#cb33-4"&gt;&lt;/a&gt;&lt;/span&gt; 658&lt;span id="cb33-4"&gt;&lt;a href="#cb33-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
531&lt;span id="cb33-5"&gt;&lt;a href="#cb33-5"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _sub_T0 = &lt;span class="dt"&gt;u32&lt;/span&gt;;&lt;/span&gt; 659&lt;span id="cb33-5"&gt;&lt;a href="#cb33-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _sub_T0 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
532&lt;span id="cb33-6"&gt;&lt;a href="#cb33-6"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _sub_T1 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; _sub_T0;&lt;/span&gt; 660&lt;span id="cb33-6"&gt;&lt;a href="#cb33-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _sub_T1 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; _sub_T0&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
533&lt;span id="cb33-7"&gt;&lt;a href="#cb33-7"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; sub( ... ) -&amp;gt; _sub_T1 &lt;span class="op"&gt;{&lt;/span&gt; ... &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 661&lt;span id="cb33-7"&gt;&lt;a href="#cb33-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; sub( &lt;span class="op"&gt;...&lt;/span&gt; ) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; _sub_T1 &lt;span class="op"&gt;{&lt;/span&gt; &lt;span class="op"&gt;...&lt;/span&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
534&lt;p&gt;Voilà! The type aliases don’t tread on each other. Remember to import &lt;code&gt;format_ident&lt;/code&gt; from the &lt;code&gt;quote&lt;/code&gt; crate.&lt;/p&gt; 662&lt;p&gt;Voilà! The type aliases don’t tread on each other. Remember to import &lt;code&gt;format_ident&lt;/code&gt; from the &lt;code&gt;quote&lt;/code&gt; crate.&lt;/p&gt;
535&lt;p&gt;&lt;strong&gt;3. The TokenStream Vector&lt;/strong&gt;&lt;/p&gt; 663&lt;p&gt;&lt;strong&gt;3. The TokenStream Vector&lt;/strong&gt;&lt;/p&gt;
536&lt;p&gt;We iterate over our types in reverse order (&lt;code&gt;T0&lt;/code&gt; is the last return, &lt;code&gt;T1&lt;/code&gt; is the second last, so on), assign a number to each iteration with &lt;code&gt;zip&lt;/code&gt;, generate type names with &lt;code&gt;format_ident&lt;/code&gt;, push a &lt;code&gt;TokenStream&lt;/code&gt; with the help of &lt;code&gt;quote&lt;/code&gt; and variable interpolation.&lt;/p&gt; 664&lt;p&gt;We iterate over our types in reverse order (&lt;code&gt;T0&lt;/code&gt; is the last return, &lt;code&gt;T1&lt;/code&gt; is the second last, so on), assign a number to each iteration with &lt;code&gt;zip&lt;/code&gt;, generate type names with &lt;code&gt;format_ident&lt;/code&gt;, push a &lt;code&gt;TokenStream&lt;/code&gt; with the help of &lt;code&gt;quote&lt;/code&gt; and variable interpolation.&lt;/p&gt;
537&lt;p&gt;If you are wondering why we used &lt;code&gt;(1..).zip()&lt;/code&gt; instead of &lt;code&gt;.enumerate()&lt;/code&gt;, it’s because we wanted to start counting from 1 instead of 0 (we are already done with &lt;code&gt;T0&lt;/code&gt;!).&lt;/p&gt; 665&lt;p&gt;If you are wondering why we used &lt;code&gt;(1..).zip()&lt;/code&gt; instead of &lt;code&gt;.enumerate()&lt;/code&gt;, it’s because we wanted to start counting from 1 instead of 0 (we are already done with &lt;code&gt;T0&lt;/code&gt;!).&lt;/p&gt;
538&lt;h4 id="getting-it-together"&gt;Getting it together&lt;/h4&gt; 666&lt;h4 id="getting-it-together"&gt;Getting it together&lt;/h4&gt;
539&lt;p&gt;I promised we’d have a fully working macro by the end of last section. I lied, we have to tie everything together in our &lt;code&gt;generate_curry&lt;/code&gt; function:&lt;/p&gt; 667&lt;p&gt;I promised we’d have a fully working macro by the end of last section. I lied, we have to tie everything together in our &lt;code&gt;generate_curry&lt;/code&gt; function:&lt;/p&gt;
540&lt;div class="sourceCode" id="cb34"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb34-1"&gt;&lt;a href="#cb34-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt; 668&lt;div class="sourceCode" id="cb34"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb34-1"&gt;&lt;a href="#cb34-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// src/lib.rs&lt;/span&gt;&lt;/span&gt;
541&lt;span id="cb34-2"&gt;&lt;a href="#cb34-2"&gt;&lt;/a&gt;&lt;/span&gt; 669&lt;span id="cb34-2"&gt;&lt;a href="#cb34-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
542&lt;span id="cb34-3"&gt;&lt;a href="#cb34-3"&gt;&lt;/a&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; generate_curry(parsed: ItemFn) -&amp;gt; &lt;span class="pp"&gt;proc_macro2::&lt;/span&gt;TokenStream &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 670&lt;span id="cb34-3"&gt;&lt;a href="#cb34-3" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; generate_curry(parsed&lt;span class="op"&gt;:&lt;/span&gt; ItemFn) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="pp"&gt;proc_macro2::&lt;/span&gt;TokenStream &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
543&lt;span id="cb34-4"&gt;&lt;a href="#cb34-4"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_body = parsed.block;&lt;/span&gt; 671&lt;span id="cb34-4"&gt;&lt;a href="#cb34-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_body &lt;span class="op"&gt;=&lt;/span&gt; parsed&lt;span class="op"&gt;.&lt;/span&gt;block&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
544&lt;span id="cb34-5"&gt;&lt;a href="#cb34-5"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; sig = parsed.sig;&lt;/span&gt; 672&lt;span id="cb34-5"&gt;&lt;a href="#cb34-5" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; sig &lt;span class="op"&gt;=&lt;/span&gt; parsed&lt;span class="op"&gt;.&lt;/span&gt;sig&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
545&lt;span id="cb34-6"&gt;&lt;a href="#cb34-6"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; vis = parsed.vis;&lt;/span&gt; 673&lt;span id="cb34-6"&gt;&lt;a href="#cb34-6" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; vis &lt;span class="op"&gt;=&lt;/span&gt; parsed&lt;span class="op"&gt;.&lt;/span&gt;vis&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
546&lt;span id="cb34-7"&gt;&lt;a href="#cb34-7"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_name = sig.ident;&lt;/span&gt; 674&lt;span id="cb34-7"&gt;&lt;a href="#cb34-7" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_name &lt;span class="op"&gt;=&lt;/span&gt; sig&lt;span class="op"&gt;.&lt;/span&gt;ident&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
547&lt;span id="cb34-8"&gt;&lt;a href="#cb34-8"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_args = sig.inputs;&lt;/span&gt; 675&lt;span id="cb34-8"&gt;&lt;a href="#cb34-8" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_args &lt;span class="op"&gt;=&lt;/span&gt; sig&lt;span class="op"&gt;.&lt;/span&gt;inputs&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
548&lt;span id="cb34-9"&gt;&lt;a href="#cb34-9"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_return_type = sig.output;&lt;/span&gt; 676&lt;span id="cb34-9"&gt;&lt;a href="#cb34-9" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; fn_return_type &lt;span class="op"&gt;=&lt;/span&gt; sig&lt;span class="op"&gt;.&lt;/span&gt;output&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
549&lt;span id="cb34-10"&gt;&lt;a href="#cb34-10"&gt;&lt;/a&gt;&lt;/span&gt; 677&lt;span id="cb34-10"&gt;&lt;a href="#cb34-10" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
550&lt;span id="cb34-11"&gt;&lt;a href="#cb34-11"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; arg_idents = extract_arg_idents(fn_args.clone());&lt;/span&gt; 678&lt;span id="cb34-11"&gt;&lt;a href="#cb34-11" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; arg_idents &lt;span class="op"&gt;=&lt;/span&gt; extract_arg_idents(fn_args&lt;span class="op"&gt;.&lt;/span&gt;clone())&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
551&lt;span id="cb34-12"&gt;&lt;a href="#cb34-12"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; first_ident = &amp;amp;arg_idents.first().unwrap();&lt;/span&gt; 679&lt;span id="cb34-12"&gt;&lt;a href="#cb34-12" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; first_ident &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="op"&gt;&amp;amp;&lt;/span&gt;arg_idents&lt;span class="op"&gt;.&lt;/span&gt;first()&lt;span class="op"&gt;.&lt;/span&gt;unwrap()&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
552&lt;span id="cb34-13"&gt;&lt;a href="#cb34-13"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; curried_body = generate_body(&amp;amp;arg_idents&lt;span class="op"&gt;[&lt;/span&gt;&lt;span class="dv"&gt;1&lt;/span&gt;..&lt;span class="op"&gt;]&lt;/span&gt;, fn_body.clone());&lt;/span&gt; 680&lt;span id="cb34-13"&gt;&lt;a href="#cb34-13" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; curried_body &lt;span class="op"&gt;=&lt;/span&gt; generate_body(&lt;span class="op"&gt;&amp;amp;&lt;/span&gt;arg_idents[&lt;span class="dv"&gt;1&lt;/span&gt;&lt;span class="op"&gt;..&lt;/span&gt;]&lt;span class="op"&gt;,&lt;/span&gt; fn_body&lt;span class="op"&gt;.&lt;/span&gt;clone())&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
553&lt;span id="cb34-14"&gt;&lt;a href="#cb34-14"&gt;&lt;/a&gt;&lt;/span&gt; 681&lt;span id="cb34-14"&gt;&lt;a href="#cb34-14" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
554&lt;span id="cb34-15"&gt;&lt;a href="#cb34-15"&gt;&lt;/a&gt;+ &lt;span class="kw"&gt;let&lt;/span&gt; arg_types = extract_arg_types(fn_args.clone());&lt;/span&gt; 682&lt;span id="cb34-15"&gt;&lt;a href="#cb34-15" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="kw"&gt;let&lt;/span&gt; arg_types &lt;span class="op"&gt;=&lt;/span&gt; extract_arg_types(fn_args&lt;span class="op"&gt;.&lt;/span&gt;clone())&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
555&lt;span id="cb34-16"&gt;&lt;a href="#cb34-16"&gt;&lt;/a&gt;+ &lt;span class="kw"&gt;let&lt;/span&gt; first_type = &amp;amp;arg_types.first().unwrap();&lt;/span&gt; 683&lt;span id="cb34-16"&gt;&lt;a href="#cb34-16" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="kw"&gt;let&lt;/span&gt; first_type &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="op"&gt;&amp;amp;&lt;/span&gt;arg_types&lt;span class="op"&gt;.&lt;/span&gt;first()&lt;span class="op"&gt;.&lt;/span&gt;unwrap()&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
556&lt;span id="cb34-17"&gt;&lt;a href="#cb34-17"&gt;&lt;/a&gt;+ &lt;span class="kw"&gt;let&lt;/span&gt; type_aliases = generate_type_aliases(&lt;/span&gt; 684&lt;span id="cb34-17"&gt;&lt;a href="#cb34-17" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="kw"&gt;let&lt;/span&gt; type_aliases &lt;span class="op"&gt;=&lt;/span&gt; generate_type_aliases(&lt;/span&gt;
557&lt;span id="cb34-18"&gt;&lt;a href="#cb34-18"&gt;&lt;/a&gt;+ &amp;amp;arg_types&lt;span class="op"&gt;[&lt;/span&gt;&lt;span class="dv"&gt;1&lt;/span&gt;..&lt;span class="op"&gt;]&lt;/span&gt;,&lt;/span&gt; 685&lt;span id="cb34-18"&gt;&lt;a href="#cb34-18" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="op"&gt;&amp;amp;&lt;/span&gt;arg_types[&lt;span class="dv"&gt;1&lt;/span&gt;&lt;span class="op"&gt;..&lt;/span&gt;]&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
558&lt;span id="cb34-19"&gt;&lt;a href="#cb34-19"&gt;&lt;/a&gt;+ extract_return_type(fn_return_type),&lt;/span&gt; 686&lt;span id="cb34-19"&gt;&lt;a href="#cb34-19" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; extract_return_type(fn_return_type)&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
559&lt;span id="cb34-20"&gt;&lt;a href="#cb34-20"&gt;&lt;/a&gt;+ &amp;amp;fn_name,&lt;/span&gt; 687&lt;span id="cb34-20"&gt;&lt;a href="#cb34-20" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="op"&gt;&amp;amp;&lt;/span&gt;fn_name&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
560&lt;span id="cb34-21"&gt;&lt;a href="#cb34-21"&gt;&lt;/a&gt;+ );&lt;/span&gt; 688&lt;span id="cb34-21"&gt;&lt;a href="#cb34-21" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; )&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
561&lt;span id="cb34-22"&gt;&lt;a href="#cb34-22"&gt;&lt;/a&gt;&lt;/span&gt; 689&lt;span id="cb34-22"&gt;&lt;a href="#cb34-22" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
562&lt;span id="cb34-23"&gt;&lt;a href="#cb34-23"&gt;&lt;/a&gt;+ &lt;span class="kw"&gt;let&lt;/span&gt; return_type = &lt;span class="pp"&gt;format_ident!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;_{}_{}&amp;quot;&lt;/span&gt;, &amp;amp;fn_name, &lt;span class="pp"&gt;format!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;T{}&amp;quot;&lt;/span&gt;, type_aliases.len() - &lt;span class="dv"&gt;1&lt;/span&gt;));&lt;/span&gt; 690&lt;span id="cb34-23"&gt;&lt;a href="#cb34-23" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="kw"&gt;let&lt;/span&gt; return_type &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="pp"&gt;format_ident!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;_{}_{}&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; &lt;span class="op"&gt;&amp;amp;&lt;/span&gt;fn_name&lt;span class="op"&gt;,&lt;/span&gt; &lt;span class="pp"&gt;format!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;T{}&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; type_aliases&lt;span class="op"&gt;.&lt;/span&gt;len() &lt;span class="op"&gt;-&lt;/span&gt; &lt;span class="dv"&gt;1&lt;/span&gt;))&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
563&lt;span id="cb34-24"&gt;&lt;a href="#cb34-24"&gt;&lt;/a&gt;&lt;/span&gt; 691&lt;span id="cb34-24"&gt;&lt;a href="#cb34-24" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
564&lt;span id="cb34-25"&gt;&lt;a href="#cb34-25"&gt;&lt;/a&gt;+ &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="pp"&gt;quote!&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 692&lt;span id="cb34-25"&gt;&lt;a href="#cb34-25" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="kw"&gt;return&lt;/span&gt; &lt;span class="pp"&gt;quote!&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
565&lt;span id="cb34-26"&gt;&lt;a href="#cb34-26"&gt;&lt;/a&gt;+ #(#type_aliases);* ;&lt;/span&gt; 693&lt;span id="cb34-26"&gt;&lt;a href="#cb34-26" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; #(#type_aliases)&lt;span class="op"&gt;;*&lt;/span&gt; &lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
566&lt;span id="cb34-27"&gt;&lt;a href="#cb34-27"&gt;&lt;/a&gt;+ #vis &lt;span class="kw"&gt;fn&lt;/span&gt; #fn_name (#first_ident: #first_type) -&amp;gt; #return_type &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 694&lt;span id="cb34-27"&gt;&lt;a href="#cb34-27" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; #vis &lt;span class="kw"&gt;fn&lt;/span&gt; #fn_name (#first_ident&lt;span class="op"&gt;:&lt;/span&gt; #first_type) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; #return_type &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
567&lt;span id="cb34-28"&gt;&lt;a href="#cb34-28"&gt;&lt;/a&gt;+ #curried_body ;&lt;/span&gt; 695&lt;span id="cb34-28"&gt;&lt;a href="#cb34-28" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; #curried_body &lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
568&lt;span id="cb34-29"&gt;&lt;a href="#cb34-29"&gt;&lt;/a&gt;+ &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 696&lt;span id="cb34-29"&gt;&lt;a href="#cb34-29" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
569&lt;span id="cb34-30"&gt;&lt;a href="#cb34-30"&gt;&lt;/a&gt;+ &lt;span class="op"&gt;}&lt;/span&gt;;&lt;/span&gt; 697&lt;span id="cb34-30"&gt;&lt;a href="#cb34-30" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;+&lt;/span&gt; &lt;span class="op"&gt;};&lt;/span&gt;&lt;/span&gt;
570&lt;span id="cb34-31"&gt;&lt;a href="#cb34-31"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 698&lt;span id="cb34-31"&gt;&lt;a href="#cb34-31" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
571&lt;p&gt;Most of the additions are self explanatory, I’ll go through the return statement with you. We are returning a &lt;code&gt;quote!{ ... }&lt;/code&gt;, so a &lt;code&gt;proc_macro2::TokenStream&lt;/code&gt;. We are iterating through the &lt;code&gt;type_aliases&lt;/code&gt; variable, which you might recall, is a &lt;code&gt;Vec&amp;lt;TokenStream&amp;gt;&lt;/code&gt;. You might notice the sneaky semicolon before the &lt;code&gt;*&lt;/code&gt;. This basically tells &lt;code&gt;quote&lt;/code&gt;, to insert an item, then a semicolon, and then the next one, another semicolon, and so on. The semicolon is a separator. We need to manually insert another semicolon at the end of it all, &lt;code&gt;quote&lt;/code&gt; doesn’t insert a separator at the end of the iteration.&lt;/p&gt; 699&lt;p&gt;Most of the additions are self explanatory, I’ll go through the return statement with you. We are returning a &lt;code&gt;quote!{ ... }&lt;/code&gt;, so a &lt;code&gt;proc_macro2::TokenStream&lt;/code&gt;. We are iterating through the &lt;code&gt;type_aliases&lt;/code&gt; variable, which you might recall, is a &lt;code&gt;Vec&amp;lt;TokenStream&amp;gt;&lt;/code&gt;. You might notice the sneaky semicolon before the &lt;code&gt;*&lt;/code&gt;. This basically tells &lt;code&gt;quote&lt;/code&gt;, to insert an item, then a semicolon, and then the next one, another semicolon, and so on. The semicolon is a separator. We need to manually insert another semicolon at the end of it all, &lt;code&gt;quote&lt;/code&gt; doesn’t insert a separator at the end of the iteration.&lt;/p&gt;
572&lt;p&gt;We retain the visibility and name of our original function. Our curried function takes as args, just the first argument of our original function. The return type of our curried function is actually, the last type alias we create. If you think back to our manually curried &lt;code&gt;add&lt;/code&gt; function, we returned &lt;code&gt;T2&lt;/code&gt;, which was in fact, the last type alias we created.&lt;/p&gt; 700&lt;p&gt;We retain the visibility and name of our original function. Our curried function takes as args, just the first argument of our original function. The return type of our curried function is actually, the last type alias we create. If you think back to our manually curried &lt;code&gt;add&lt;/code&gt; function, we returned &lt;code&gt;T2&lt;/code&gt;, which was in fact, the last type alias we created.&lt;/p&gt;
573&lt;p&gt;I am sure, at this point, you are itching to test this out, but before that, let me introduce you to some good methods of debugging proc-macro code.&lt;/p&gt; 701&lt;p&gt;I am sure, at this point, you are itching to test this out, but before that, let me introduce you to some good methods of debugging proc-macro code.&lt;/p&gt;
@@ -599,57 +727,57 @@ fn main() {
599&lt;p&gt;Writing proc-macros without &lt;code&gt;cargo-expand&lt;/code&gt; is tantamount to driving a vehicle without rear view mirrors! Keep an eye on what is going on behind your back.&lt;/p&gt; 727&lt;p&gt;Writing proc-macros without &lt;code&gt;cargo-expand&lt;/code&gt; is tantamount to driving a vehicle without rear view mirrors! Keep an eye on what is going on behind your back.&lt;/p&gt;
600&lt;p&gt;Now, your macro won’t always compile, you might just recieve the bee movie script as an error. &lt;code&gt;cargo-expand&lt;/code&gt; will not work in such cases. I would suggest printing out your variables to inspect them. &lt;code&gt;TokenStream&lt;/code&gt; implements &lt;code&gt;Display&lt;/code&gt; as well as &lt;code&gt;Debug&lt;/code&gt;. We don’t always have to be respectable programmers. Just print it.&lt;/p&gt; 728&lt;p&gt;Now, your macro won’t always compile, you might just recieve the bee movie script as an error. &lt;code&gt;cargo-expand&lt;/code&gt; will not work in such cases. I would suggest printing out your variables to inspect them. &lt;code&gt;TokenStream&lt;/code&gt; implements &lt;code&gt;Display&lt;/code&gt; as well as &lt;code&gt;Debug&lt;/code&gt;. We don’t always have to be respectable programmers. Just print it.&lt;/p&gt;
601&lt;p&gt;Enough of that, lets get testing:&lt;/p&gt; 729&lt;p&gt;Enough of that, lets get testing:&lt;/p&gt;
602&lt;div class="sourceCode" id="cb37"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb37-1"&gt;&lt;a href="#cb37-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;// tests/smoke.rs&lt;/span&gt;&lt;/span&gt; 730&lt;div class="sourceCode" id="cb37"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb37-1"&gt;&lt;a href="#cb37-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// tests/smoke.rs&lt;/span&gt;&lt;/span&gt;
603&lt;span id="cb37-2"&gt;&lt;a href="#cb37-2"&gt;&lt;/a&gt;&lt;/span&gt; 731&lt;span id="cb37-2"&gt;&lt;a href="#cb37-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
604&lt;span id="cb37-3"&gt;&lt;a href="#cb37-3"&gt;&lt;/a&gt;&lt;span class="at"&gt;#![&lt;/span&gt;feature&lt;span class="at"&gt;(&lt;/span&gt;type_alias_impl_trait&lt;span class="at"&gt;)]&lt;/span&gt;&lt;/span&gt; 732&lt;span id="cb37-3"&gt;&lt;a href="#cb37-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="at"&gt;#![&lt;/span&gt;feature&lt;span class="at"&gt;(&lt;/span&gt;type_alias_impl_trait&lt;span class="at"&gt;)]&lt;/span&gt;&lt;/span&gt;
605&lt;span id="cb37-4"&gt;&lt;a href="#cb37-4"&gt;&lt;/a&gt;&lt;/span&gt; 733&lt;span id="cb37-4"&gt;&lt;a href="#cb37-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
606&lt;span id="cb37-5"&gt;&lt;a href="#cb37-5"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;&lt;span class="pp"&gt;crate_name::&lt;/span&gt;curry&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt; 734&lt;span id="cb37-5"&gt;&lt;a href="#cb37-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;&lt;span class="pp"&gt;crate_name::&lt;/span&gt;curry&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt;
607&lt;span id="cb37-6"&gt;&lt;a href="#cb37-6"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x: &lt;span class="dt"&gt;u32&lt;/span&gt;, y: &lt;span class="dt"&gt;u32&lt;/span&gt;, z: &lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 735&lt;span id="cb37-6"&gt;&lt;a href="#cb37-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; y&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; z&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
608&lt;span id="cb37-7"&gt;&lt;a href="#cb37-7"&gt;&lt;/a&gt; x + y + z&lt;/span&gt; 736&lt;span id="cb37-7"&gt;&lt;a href="#cb37-7" aria-hidden="true"&gt;&lt;/a&gt; x &lt;span class="op"&gt;+&lt;/span&gt; y &lt;span class="op"&gt;+&lt;/span&gt; z&lt;/span&gt;
609&lt;span id="cb37-8"&gt;&lt;a href="#cb37-8"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 737&lt;span id="cb37-8"&gt;&lt;a href="#cb37-8" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
610&lt;span id="cb37-9"&gt;&lt;a href="#cb37-9"&gt;&lt;/a&gt;&lt;/span&gt; 738&lt;span id="cb37-9"&gt;&lt;a href="#cb37-9" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
611&lt;span id="cb37-10"&gt;&lt;a href="#cb37-10"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;test&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt; 739&lt;span id="cb37-10"&gt;&lt;a href="#cb37-10" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;test&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt;
612&lt;span id="cb37-11"&gt;&lt;a href="#cb37-11"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; works() &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 740&lt;span id="cb37-11"&gt;&lt;a href="#cb37-11" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; works() &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
613&lt;span id="cb37-12"&gt;&lt;a href="#cb37-12"&gt;&lt;/a&gt; &lt;span class="pp"&gt;assert_eq!&lt;/span&gt;(&lt;span class="dv"&gt;15&lt;/span&gt;, add(&lt;span class="dv"&gt;4&lt;/span&gt;)(&lt;span class="dv"&gt;5&lt;/span&gt;)(&lt;span class="dv"&gt;6&lt;/span&gt;));&lt;/span&gt; 741&lt;span id="cb37-12"&gt;&lt;a href="#cb37-12" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="pp"&gt;assert_eq!&lt;/span&gt;(&lt;span class="dv"&gt;15&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; add(&lt;span class="dv"&gt;4&lt;/span&gt;)(&lt;span class="dv"&gt;5&lt;/span&gt;)(&lt;span class="dv"&gt;6&lt;/span&gt;))&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
614&lt;span id="cb37-13"&gt;&lt;a href="#cb37-13"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 742&lt;span id="cb37-13"&gt;&lt;a href="#cb37-13" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
615&lt;p&gt;Run &lt;code&gt;cargo +nightly test&lt;/code&gt;. You should see a pleasing message:&lt;/p&gt; 743&lt;p&gt;Run &lt;code&gt;cargo +nightly test&lt;/code&gt;. You should see a pleasing message:&lt;/p&gt;
616&lt;pre&gt;&lt;code&gt;running 1 test 744&lt;pre&gt;&lt;code&gt;running 1 test
617test tests::works ... ok&lt;/code&gt;&lt;/pre&gt; 745test tests::works ... ok&lt;/code&gt;&lt;/pre&gt;
618&lt;p&gt;Take a look at the expansion for our curry macro, via &lt;code&gt;cargo +nightly expand --tests smoke&lt;/code&gt;:&lt;/p&gt; 746&lt;p&gt;Take a look at the expansion for our curry macro, via &lt;code&gt;cargo +nightly expand --tests smoke&lt;/code&gt;:&lt;/p&gt;
619&lt;div class="sourceCode" id="cb39"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb39-1"&gt;&lt;a href="#cb39-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _add_T0 = &lt;span class="dt"&gt;u32&lt;/span&gt;;&lt;/span&gt; 747&lt;div class="sourceCode" id="cb39"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb39-1"&gt;&lt;a href="#cb39-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _add_T0 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
620&lt;span id="cb39-2"&gt;&lt;a href="#cb39-2"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _add_T1 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; _add_T0;&lt;/span&gt; 748&lt;span id="cb39-2"&gt;&lt;a href="#cb39-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _add_T1 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; _add_T0&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
621&lt;span id="cb39-3"&gt;&lt;a href="#cb39-3"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _add_T2 = &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; _add_T1;&lt;/span&gt; 749&lt;span id="cb39-3"&gt;&lt;a href="#cb39-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;type&lt;/span&gt; _add_T2 &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="kw"&gt;impl&lt;/span&gt; &lt;span class="bu"&gt;Fn&lt;/span&gt;(&lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; _add_T1&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
622&lt;span id="cb39-4"&gt;&lt;a href="#cb39-4"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x: &lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; _add_T2 &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 750&lt;span id="cb39-4"&gt;&lt;a href="#cb39-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; add(x&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; _add_T2 &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
623&lt;span id="cb39-5"&gt;&lt;a href="#cb39-5"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; (&lt;span class="kw"&gt;move&lt;/span&gt; |y| &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 751&lt;span id="cb39-5"&gt;&lt;a href="#cb39-5" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; (&lt;span class="kw"&gt;move&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;y&lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
624&lt;span id="cb39-6"&gt;&lt;a href="#cb39-6"&gt;&lt;/a&gt; &lt;span class="kw"&gt;move&lt;/span&gt; |z| &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 752&lt;span id="cb39-6"&gt;&lt;a href="#cb39-6" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;move&lt;/span&gt; &lt;span class="op"&gt;|&lt;/span&gt;z&lt;span class="op"&gt;|&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
625&lt;span id="cb39-7"&gt;&lt;a href="#cb39-7"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; x + y + z;&lt;/span&gt; 753&lt;span id="cb39-7"&gt;&lt;a href="#cb39-7" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; x &lt;span class="op"&gt;+&lt;/span&gt; y &lt;span class="op"&gt;+&lt;/span&gt; z&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
626&lt;span id="cb39-8"&gt;&lt;a href="#cb39-8"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 754&lt;span id="cb39-8"&gt;&lt;a href="#cb39-8" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
627&lt;span id="cb39-9"&gt;&lt;a href="#cb39-9"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;);&lt;/span&gt; 755&lt;span id="cb39-9"&gt;&lt;a href="#cb39-9" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;)&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
628&lt;span id="cb39-10"&gt;&lt;a href="#cb39-10"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 756&lt;span id="cb39-10"&gt;&lt;a href="#cb39-10" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
629&lt;span id="cb39-11"&gt;&lt;a href="#cb39-11"&gt;&lt;/a&gt;&lt;/span&gt; 757&lt;span id="cb39-11"&gt;&lt;a href="#cb39-11" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
630&lt;span id="cb39-12"&gt;&lt;a href="#cb39-12"&gt;&lt;/a&gt;&lt;span class="co"&gt;// a bunch of other stuff generated by #[test] and assert_eq!&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 758&lt;span id="cb39-12"&gt;&lt;a href="#cb39-12" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;// a bunch of other stuff generated by #[test] and assert_eq!&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
631&lt;p&gt;A sight for sore eyes.&lt;/p&gt; 759&lt;p&gt;A sight for sore eyes.&lt;/p&gt;
632&lt;p&gt;Here is a more complex example that generates ten multiples of the first ten natural numbers:&lt;/p&gt; 760&lt;p&gt;Here is a more complex example that generates ten multiples of the first ten natural numbers:&lt;/p&gt;
633&lt;div class="sourceCode" id="cb40"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb40-1"&gt;&lt;a href="#cb40-1"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;curry&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt; 761&lt;div class="sourceCode" id="cb40"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb40-1"&gt;&lt;a href="#cb40-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="at"&gt;#[&lt;/span&gt;curry&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt;
634&lt;span id="cb40-2"&gt;&lt;a href="#cb40-2"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; product(x: &lt;span class="dt"&gt;u32&lt;/span&gt;, y: &lt;span class="dt"&gt;u32&lt;/span&gt;) -&amp;gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 762&lt;span id="cb40-2"&gt;&lt;a href="#cb40-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; product(x&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; y&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt;) &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;u32&lt;/span&gt; &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
635&lt;span id="cb40-3"&gt;&lt;a href="#cb40-3"&gt;&lt;/a&gt; x * y&lt;/span&gt; 763&lt;span id="cb40-3"&gt;&lt;a href="#cb40-3" aria-hidden="true"&gt;&lt;/a&gt; x &lt;span class="op"&gt;*&lt;/span&gt; y&lt;/span&gt;
636&lt;span id="cb40-4"&gt;&lt;a href="#cb40-4"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 764&lt;span id="cb40-4"&gt;&lt;a href="#cb40-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
637&lt;span id="cb40-5"&gt;&lt;a href="#cb40-5"&gt;&lt;/a&gt;&lt;/span&gt; 765&lt;span id="cb40-5"&gt;&lt;a href="#cb40-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
638&lt;span id="cb40-6"&gt;&lt;a href="#cb40-6"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; multiples() -&amp;gt; &lt;span class="dt"&gt;Vec&lt;/span&gt;&amp;lt;&lt;span class="dt"&gt;Vec&lt;/span&gt;&amp;lt;&lt;span class="dt"&gt;u32&lt;/span&gt;&amp;gt;&amp;gt;&lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 766&lt;span id="cb40-6"&gt;&lt;a href="#cb40-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;fn&lt;/span&gt; multiples() &lt;span class="op"&gt;-&amp;gt;&lt;/span&gt; &lt;span class="dt"&gt;Vec&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="dt"&gt;Vec&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;&lt;span class="dt"&gt;u32&lt;/span&gt;&lt;span class="op"&gt;&amp;gt;&amp;gt;{&lt;/span&gt;&lt;/span&gt;
639&lt;span id="cb40-7"&gt;&lt;a href="#cb40-7"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; v = (&lt;span class="dv"&gt;1&lt;/span&gt;..=&lt;span class="dv"&gt;10&lt;/span&gt;).map(product);&lt;/span&gt; 767&lt;span id="cb40-7"&gt;&lt;a href="#cb40-7" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; v &lt;span class="op"&gt;=&lt;/span&gt; (&lt;span class="dv"&gt;1&lt;/span&gt;&lt;span class="op"&gt;..=&lt;/span&gt;&lt;span class="dv"&gt;10&lt;/span&gt;)&lt;span class="op"&gt;.&lt;/span&gt;map(product)&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
640&lt;span id="cb40-8"&gt;&lt;a href="#cb40-8"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; (&lt;span class="dv"&gt;1&lt;/span&gt;..=&lt;span class="dv"&gt;10&lt;/span&gt;)&lt;/span&gt; 768&lt;span id="cb40-8"&gt;&lt;a href="#cb40-8" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;return&lt;/span&gt; (&lt;span class="dv"&gt;1&lt;/span&gt;&lt;span class="op"&gt;..=&lt;/span&gt;&lt;span class="dv"&gt;10&lt;/span&gt;)&lt;/span&gt;
641&lt;span id="cb40-9"&gt;&lt;a href="#cb40-9"&gt;&lt;/a&gt; .map(|x| v.clone().map(|f| f(x)).collect())&lt;/span&gt; 769&lt;span id="cb40-9"&gt;&lt;a href="#cb40-9" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;.&lt;/span&gt;map(&lt;span class="op"&gt;|&lt;/span&gt;x&lt;span class="op"&gt;|&lt;/span&gt; v&lt;span class="op"&gt;.&lt;/span&gt;clone()&lt;span class="op"&gt;.&lt;/span&gt;map(&lt;span class="op"&gt;|&lt;/span&gt;f&lt;span class="op"&gt;|&lt;/span&gt; f(x))&lt;span class="op"&gt;.&lt;/span&gt;collect())&lt;/span&gt;
642&lt;span id="cb40-10"&gt;&lt;a href="#cb40-10"&gt;&lt;/a&gt; .collect();&lt;/span&gt; 770&lt;span id="cb40-10"&gt;&lt;a href="#cb40-10" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;.&lt;/span&gt;collect()&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
643&lt;span id="cb40-11"&gt;&lt;a href="#cb40-11"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 771&lt;span id="cb40-11"&gt;&lt;a href="#cb40-11" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
644&lt;h3 id="notes"&gt;Notes&lt;/h3&gt; 772&lt;h3 id="notes"&gt;Notes&lt;/h3&gt;
645&lt;p&gt;I didn’t quite explain why we use &lt;code&gt;move |arg|&lt;/code&gt; in our closure. This is because we want to take ownership of the variable supplied to us. Take a look at this example:&lt;/p&gt; 773&lt;p&gt;I didn’t quite explain why we use &lt;code&gt;move |arg|&lt;/code&gt; in our closure. This is because we want to take ownership of the variable supplied to us. Take a look at this example:&lt;/p&gt;
646&lt;div class="sourceCode" id="cb41"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb41-1"&gt;&lt;a href="#cb41-1"&gt;&lt;/a&gt;&lt;span class="kw"&gt;let&lt;/span&gt; v = add(&lt;span class="dv"&gt;5&lt;/span&gt;);&lt;/span&gt; 774&lt;div class="sourceCode" id="cb41"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb41-1"&gt;&lt;a href="#cb41-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;let&lt;/span&gt; v &lt;span class="op"&gt;=&lt;/span&gt; add(&lt;span class="dv"&gt;5&lt;/span&gt;)&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
647&lt;span id="cb41-2"&gt;&lt;a href="#cb41-2"&gt;&lt;/a&gt;&lt;span class="kw"&gt;let&lt;/span&gt; g;&lt;/span&gt; 775&lt;span id="cb41-2"&gt;&lt;a href="#cb41-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;let&lt;/span&gt; g&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
648&lt;span id="cb41-3"&gt;&lt;a href="#cb41-3"&gt;&lt;/a&gt;&lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 776&lt;span id="cb41-3"&gt;&lt;a href="#cb41-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
649&lt;span id="cb41-4"&gt;&lt;a href="#cb41-4"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; x = &lt;span class="dv"&gt;5&lt;/span&gt;;&lt;/span&gt; 777&lt;span id="cb41-4"&gt;&lt;a href="#cb41-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;let&lt;/span&gt; x &lt;span class="op"&gt;=&lt;/span&gt; &lt;span class="dv"&gt;5&lt;/span&gt;&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
650&lt;span id="cb41-5"&gt;&lt;a href="#cb41-5"&gt;&lt;/a&gt; g = v(x);&lt;/span&gt; 778&lt;span id="cb41-5"&gt;&lt;a href="#cb41-5" aria-hidden="true"&gt;&lt;/a&gt; g &lt;span class="op"&gt;=&lt;/span&gt; v(x)&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
651&lt;span id="cb41-6"&gt;&lt;a href="#cb41-6"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt; 779&lt;span id="cb41-6"&gt;&lt;a href="#cb41-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;
652&lt;span id="cb41-7"&gt;&lt;a href="#cb41-7"&gt;&lt;/a&gt;&lt;span class="pp"&gt;println!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;{}&amp;quot;&lt;/span&gt;, g(&lt;span class="dv"&gt;2&lt;/span&gt;));&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 780&lt;span id="cb41-7"&gt;&lt;a href="#cb41-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="pp"&gt;println!&lt;/span&gt;(&lt;span class="st"&gt;&amp;quot;{}&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;,&lt;/span&gt; g(&lt;span class="dv"&gt;2&lt;/span&gt;))&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
653&lt;p&gt;Variable &lt;code&gt;x&lt;/code&gt; goes out of scope before &lt;code&gt;g&lt;/code&gt; can return a concrete value. If we take ownership of &lt;code&gt;x&lt;/code&gt; by &lt;code&gt;move&lt;/code&gt;ing it into our closure, we can expect this to work reliably. In fact, rustc understands this, and forces you to use &lt;code&gt;move&lt;/code&gt;.&lt;/p&gt; 781&lt;p&gt;Variable &lt;code&gt;x&lt;/code&gt; goes out of scope before &lt;code&gt;g&lt;/code&gt; can return a concrete value. If we take ownership of &lt;code&gt;x&lt;/code&gt; by &lt;code&gt;move&lt;/code&gt;ing it into our closure, we can expect this to work reliably. In fact, rustc understands this, and forces you to use &lt;code&gt;move&lt;/code&gt;.&lt;/p&gt;
654&lt;p&gt;This usage of &lt;code&gt;move&lt;/code&gt; is exactly why &lt;strong&gt;a curried function without a return is useless&lt;/strong&gt;. Every variable we pass to our curried function gets moved into its local scope. Playing with these variables cannot cause a change outside this scope. Returning is our only method of interaction with anything beyond this function.&lt;/p&gt; 782&lt;p&gt;This usage of &lt;code&gt;move&lt;/code&gt; is exactly why &lt;strong&gt;a curried function without a return is useless&lt;/strong&gt;. Every variable we pass to our curried function gets moved into its local scope. Playing with these variables cannot cause a change outside this scope. Returning is our only method of interaction with anything beyond this function.&lt;/p&gt;
655&lt;h3 id="conclusion"&gt;Conclusion&lt;/h3&gt; 783&lt;h3 id="conclusion"&gt;Conclusion&lt;/h3&gt;
@@ -678,7 +806,7 @@ test tests::works ... ok&lt;/code&gt;&lt;/pre&gt;
678&lt;h3 id="choosing-a-brush"&gt;Choosing a Brush&lt;/h3&gt; 806&lt;h3 id="choosing-a-brush"&gt;Choosing a Brush&lt;/h3&gt;
679&lt;p&gt;The most important part of our setup is the brush. Use the Pencil Tool (&lt;code&gt;n&lt;/code&gt; on the keyboard) for hard edge drawings. Here’s a small comparison if you don’t know the difference between a hard edge and a soft edge:&lt;/p&gt; 807&lt;p&gt;The most important part of our setup is the brush. Use the Pencil Tool (&lt;code&gt;n&lt;/code&gt; on the keyboard) for hard edge drawings. Here’s a small comparison if you don’t know the difference between a hard edge and a soft edge:&lt;/p&gt;
680&lt;figure&gt; 808&lt;figure&gt;
681&lt;img src="https://u.peppe.rs/kz.png" alt="" /&gt;&lt;figcaption&gt;Hard edge vs Soft Edge&lt;/figcaption&gt; 809&lt;img src="https://u.peppe.rs/kz.png" alt="Hard edge vs Soft Edge" /&gt;&lt;figcaption aria-hidden="true"&gt;Hard edge vs Soft Edge&lt;/figcaption&gt;
682&lt;/figure&gt; 810&lt;/figure&gt;
683&lt;p&gt;I turn the size down all the way to 1 (&lt;code&gt;[&lt;/code&gt; on the keyboard). Set &lt;code&gt;Dynamics&lt;/code&gt; off. &lt;a href="https://u.peppe.rs/Fs.png"&gt;Here’s&lt;/a&gt; a sample brush configuration.&lt;/p&gt; 811&lt;p&gt;I turn the size down all the way to 1 (&lt;code&gt;[&lt;/code&gt; on the keyboard). Set &lt;code&gt;Dynamics&lt;/code&gt; off. &lt;a href="https://u.peppe.rs/Fs.png"&gt;Here’s&lt;/a&gt; a sample brush configuration.&lt;/p&gt;
684&lt;h3 id="laying-down-the-pixels"&gt;Laying down the pixels!&lt;/h3&gt; 812&lt;h3 id="laying-down-the-pixels"&gt;Laying down the pixels!&lt;/h3&gt;
@@ -726,34 +854,34 @@ test tests::works ... ok&lt;/code&gt;&lt;/pre&gt;
726<title>Rapid Refactoring With Vim</title> 854<title>Rapid Refactoring With Vim</title>
727<description>&lt;p&gt;Last weekend, I was tasked with refactoring the 96 unit tests on &lt;a href="https://github.com/ruma/ruma-events/pull/70"&gt;ruma-events&lt;/a&gt; to use strictly typed json objects using &lt;code&gt;serde_json::json!&lt;/code&gt; instead of raw strings. It was rather painless thanks to vim :)&lt;/p&gt; 855<description>&lt;p&gt;Last weekend, I was tasked with refactoring the 96 unit tests on &lt;a href="https://github.com/ruma/ruma-events/pull/70"&gt;ruma-events&lt;/a&gt; to use strictly typed json objects using &lt;code&gt;serde_json::json!&lt;/code&gt; instead of raw strings. It was rather painless thanks to vim :)&lt;/p&gt;
728&lt;p&gt;Here’s a small sample of what had to be done (note the lines prefixed with the arrow):&lt;/p&gt; 856&lt;p&gt;Here’s a small sample of what had to be done (note the lines prefixed with the arrow):&lt;/p&gt;
729&lt;div class="sourceCode" id="cb1"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb1-1"&gt;&lt;a href="#cb1-1"&gt;&lt;/a&gt;→ &lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;serde_json::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;from_str&lt;span class="op"&gt;}&lt;/span&gt;;&lt;/span&gt; 857&lt;div class="sourceCode" id="cb1"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb1-1"&gt;&lt;a href="#cb1-1" aria-hidden="true"&gt;&lt;/a&gt;→ &lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;serde_json::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;from_str&lt;span class="op"&gt;};&lt;/span&gt;&lt;/span&gt;
730&lt;span id="cb1-2"&gt;&lt;a href="#cb1-2"&gt;&lt;/a&gt; &lt;/span&gt; 858&lt;span id="cb1-2"&gt;&lt;a href="#cb1-2" aria-hidden="true"&gt;&lt;/a&gt; &lt;/span&gt;
731&lt;span id="cb1-3"&gt;&lt;a href="#cb1-3"&gt;&lt;/a&gt; &lt;span class="at"&gt;#[&lt;/span&gt;test&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt; 859&lt;span id="cb1-3"&gt;&lt;a href="#cb1-3" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="at"&gt;#[&lt;/span&gt;test&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt;
732&lt;span id="cb1-4"&gt;&lt;a href="#cb1-4"&gt;&lt;/a&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; deserialize() &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 860&lt;span id="cb1-4"&gt;&lt;a href="#cb1-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; deserialize() &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
733&lt;span id="cb1-5"&gt;&lt;a href="#cb1-5"&gt;&lt;/a&gt; &lt;span class="pp"&gt;assert_eq!&lt;/span&gt;(&lt;/span&gt; 861&lt;span id="cb1-5"&gt;&lt;a href="#cb1-5" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="pp"&gt;assert_eq!&lt;/span&gt;(&lt;/span&gt;
734&lt;span id="cb1-6"&gt;&lt;a href="#cb1-6"&gt;&lt;/a&gt;→ &lt;span class="pp"&gt;from_str::&lt;/span&gt;&amp;lt;Action&amp;gt;(&lt;span class="st"&gt;r#&amp;quot;{&amp;quot;set_tweak&amp;quot;: &amp;quot;highlight&amp;quot;}&amp;quot;#&lt;/span&gt;),&lt;/span&gt; 862&lt;span id="cb1-6"&gt;&lt;a href="#cb1-6" aria-hidden="true"&gt;&lt;/a&gt;→ &lt;span class="pp"&gt;from_str::&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;Action&lt;span class="op"&gt;&amp;gt;&lt;/span&gt;(&lt;span class="st"&gt;r#&amp;quot;{&amp;quot;set_tweak&amp;quot;: &amp;quot;highlight&amp;quot;}&amp;quot;#&lt;/span&gt;)&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
735&lt;span id="cb1-7"&gt;&lt;a href="#cb1-7"&gt;&lt;/a&gt; &lt;span class="pp"&gt;Action::&lt;/span&gt;SetTweak(&lt;span class="pp"&gt;Tweak::&lt;/span&gt;Highlight &lt;span class="op"&gt;{&lt;/span&gt; value: &lt;span class="cn"&gt;true&lt;/span&gt; &lt;span class="op"&gt;}&lt;/span&gt;)&lt;/span&gt; 863&lt;span id="cb1-7"&gt;&lt;a href="#cb1-7" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="pp"&gt;Action::&lt;/span&gt;SetTweak(&lt;span class="pp"&gt;Tweak::&lt;/span&gt;Highlight &lt;span class="op"&gt;{&lt;/span&gt; value&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="cn"&gt;true&lt;/span&gt; &lt;span class="op"&gt;}&lt;/span&gt;)&lt;/span&gt;
736&lt;span id="cb1-8"&gt;&lt;a href="#cb1-8"&gt;&lt;/a&gt; );&lt;/span&gt; 864&lt;span id="cb1-8"&gt;&lt;a href="#cb1-8" aria-hidden="true"&gt;&lt;/a&gt; )&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
737&lt;span id="cb1-9"&gt;&lt;a href="#cb1-9"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 865&lt;span id="cb1-9"&gt;&lt;a href="#cb1-9" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
738&lt;p&gt;had to be converted to:&lt;/p&gt; 866&lt;p&gt;had to be converted to:&lt;/p&gt;
739&lt;div class="sourceCode" id="cb2"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb2-1"&gt;&lt;a href="#cb2-1"&gt;&lt;/a&gt;→ &lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;serde_json::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;from_value&lt;span class="op"&gt;}&lt;/span&gt;;&lt;/span&gt; 867&lt;div class="sourceCode" id="cb2"&gt;&lt;pre class="sourceCode rust"&gt;&lt;code class="sourceCode rust"&gt;&lt;span id="cb2-1"&gt;&lt;a href="#cb2-1" aria-hidden="true"&gt;&lt;/a&gt;→ &lt;span class="kw"&gt;use&lt;/span&gt; &lt;span class="pp"&gt;serde_json::&lt;/span&gt;&lt;span class="op"&gt;{&lt;/span&gt;from_value&lt;span class="op"&gt;};&lt;/span&gt;&lt;/span&gt;
740&lt;span id="cb2-2"&gt;&lt;a href="#cb2-2"&gt;&lt;/a&gt; &lt;/span&gt; 868&lt;span id="cb2-2"&gt;&lt;a href="#cb2-2" aria-hidden="true"&gt;&lt;/a&gt; &lt;/span&gt;
741&lt;span id="cb2-3"&gt;&lt;a href="#cb2-3"&gt;&lt;/a&gt; &lt;span class="at"&gt;#[&lt;/span&gt;test&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt; 869&lt;span id="cb2-3"&gt;&lt;a href="#cb2-3" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="at"&gt;#[&lt;/span&gt;test&lt;span class="at"&gt;]&lt;/span&gt;&lt;/span&gt;
742&lt;span id="cb2-4"&gt;&lt;a href="#cb2-4"&gt;&lt;/a&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; deserialize() &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt; 870&lt;span id="cb2-4"&gt;&lt;a href="#cb2-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="kw"&gt;fn&lt;/span&gt; deserialize() &lt;span class="op"&gt;{&lt;/span&gt;&lt;/span&gt;
743&lt;span id="cb2-5"&gt;&lt;a href="#cb2-5"&gt;&lt;/a&gt; &lt;span class="pp"&gt;assert_eq!&lt;/span&gt;(&lt;/span&gt; 871&lt;span id="cb2-5"&gt;&lt;a href="#cb2-5" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="pp"&gt;assert_eq!&lt;/span&gt;(&lt;/span&gt;
744&lt;span id="cb2-6"&gt;&lt;a href="#cb2-6"&gt;&lt;/a&gt;→ &lt;span class="pp"&gt;from_value::&lt;/span&gt;&amp;lt;Action&amp;gt;(&lt;span class="pp"&gt;json!&lt;/span&gt;(&lt;span class="op"&gt;{&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;set_tweak&amp;quot;&lt;/span&gt;: &lt;span class="st"&gt;&amp;quot;highlight&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;}&lt;/span&gt;)),&lt;/span&gt; 872&lt;span id="cb2-6"&gt;&lt;a href="#cb2-6" aria-hidden="true"&gt;&lt;/a&gt;→ &lt;span class="pp"&gt;from_value::&lt;/span&gt;&lt;span class="op"&gt;&amp;lt;&lt;/span&gt;Action&lt;span class="op"&gt;&amp;gt;&lt;/span&gt;(&lt;span class="pp"&gt;json!&lt;/span&gt;(&lt;span class="op"&gt;{&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;set_tweak&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;highlight&amp;quot;&lt;/span&gt;&lt;span class="op"&gt;}&lt;/span&gt;))&lt;span class="op"&gt;,&lt;/span&gt;&lt;/span&gt;
745&lt;span id="cb2-7"&gt;&lt;a href="#cb2-7"&gt;&lt;/a&gt; &lt;span class="pp"&gt;Action::&lt;/span&gt;SetTweak(&lt;span class="pp"&gt;Tweak::&lt;/span&gt;Highlight &lt;span class="op"&gt;{&lt;/span&gt; value: &lt;span class="cn"&gt;true&lt;/span&gt; &lt;span class="op"&gt;}&lt;/span&gt;)&lt;/span&gt; 873&lt;span id="cb2-7"&gt;&lt;a href="#cb2-7" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="pp"&gt;Action::&lt;/span&gt;SetTweak(&lt;span class="pp"&gt;Tweak::&lt;/span&gt;Highlight &lt;span class="op"&gt;{&lt;/span&gt; value&lt;span class="op"&gt;:&lt;/span&gt; &lt;span class="cn"&gt;true&lt;/span&gt; &lt;span class="op"&gt;}&lt;/span&gt;)&lt;/span&gt;
746&lt;span id="cb2-8"&gt;&lt;a href="#cb2-8"&gt;&lt;/a&gt; );&lt;/span&gt; 874&lt;span id="cb2-8"&gt;&lt;a href="#cb2-8" aria-hidden="true"&gt;&lt;/a&gt; )&lt;span class="op"&gt;;&lt;/span&gt;&lt;/span&gt;
747&lt;span id="cb2-9"&gt;&lt;a href="#cb2-9"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 875&lt;span id="cb2-9"&gt;&lt;a href="#cb2-9" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="op"&gt;}&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
748&lt;h3 id="the-arglist"&gt;The arglist&lt;/h3&gt; 876&lt;h3 id="the-arglist"&gt;The arglist&lt;/h3&gt;
749&lt;p&gt;For the initial pass, I decided to handle imports, this was a simple find and replace operation, done to all the files containing tests. Luckily, modules (and therefore files) containing tests in Rust are annotated with the &lt;code&gt;#[cfg(test)]&lt;/code&gt; attribute. I opened all such files:&lt;/p&gt; 877&lt;p&gt;For the initial pass, I decided to handle imports, this was a simple find and replace operation, done to all the files containing tests. Luckily, modules (and therefore files) containing tests in Rust are annotated with the &lt;code&gt;#[cfg(test)]&lt;/code&gt; attribute. I opened all such files:&lt;/p&gt;
750&lt;div class="sourceCode" id="cb3"&gt;&lt;pre class="sourceCode bash"&gt;&lt;code class="sourceCode bash"&gt;&lt;span id="cb3-1"&gt;&lt;a href="#cb3-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;# `grep -l pattern files` lists all the files&lt;/span&gt;&lt;/span&gt; 878&lt;div class="sourceCode" id="cb3"&gt;&lt;pre class="sourceCode bash"&gt;&lt;code class="sourceCode bash"&gt;&lt;span id="cb3-1"&gt;&lt;a href="#cb3-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;# `grep -l pattern files` lists all the files&lt;/span&gt;&lt;/span&gt;
751&lt;span id="cb3-2"&gt;&lt;a href="#cb3-2"&gt;&lt;/a&gt;&lt;span class="co"&gt;# matching the pattern&lt;/span&gt;&lt;/span&gt; 879&lt;span id="cb3-2"&gt;&lt;a href="#cb3-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;# matching the pattern&lt;/span&gt;&lt;/span&gt;
752&lt;span id="cb3-3"&gt;&lt;a href="#cb3-3"&gt;&lt;/a&gt;&lt;/span&gt; 880&lt;span id="cb3-3"&gt;&lt;a href="#cb3-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
753&lt;span id="cb3-4"&gt;&lt;a href="#cb3-4"&gt;&lt;/a&gt;&lt;span class="ex"&gt;vim&lt;/span&gt; &lt;span class="va"&gt;$(&lt;/span&gt;&lt;span class="fu"&gt;grep&lt;/span&gt; -l &lt;span class="st"&gt;&amp;#39;cfg\(test\)&amp;#39;&lt;/span&gt; ./**/*.rs&lt;span class="va"&gt;)&lt;/span&gt;&lt;/span&gt; 881&lt;span id="cb3-4"&gt;&lt;a href="#cb3-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="ex"&gt;vim&lt;/span&gt; &lt;span class="va"&gt;$(&lt;/span&gt;&lt;span class="fu"&gt;grep&lt;/span&gt; -l &lt;span class="st"&gt;&amp;#39;cfg\(test\)&amp;#39;&lt;/span&gt; ./**/*.rs&lt;span class="va"&gt;)&lt;/span&gt;&lt;/span&gt;
754&lt;span id="cb3-5"&gt;&lt;a href="#cb3-5"&gt;&lt;/a&gt;&lt;/span&gt; 882&lt;span id="cb3-5"&gt;&lt;a href="#cb3-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
755&lt;span id="cb3-6"&gt;&lt;a href="#cb3-6"&gt;&lt;/a&gt;&lt;span class="co"&gt;# expands to something like:&lt;/span&gt;&lt;/span&gt; 883&lt;span id="cb3-6"&gt;&lt;a href="#cb3-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;# expands to something like:&lt;/span&gt;&lt;/span&gt;
756&lt;span id="cb3-7"&gt;&lt;a href="#cb3-7"&gt;&lt;/a&gt;&lt;span class="ex"&gt;vim&lt;/span&gt; push_rules.rs room/member.rs key/verification/lib.rs&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 884&lt;span id="cb3-7"&gt;&lt;a href="#cb3-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="ex"&gt;vim&lt;/span&gt; push_rules.rs room/member.rs key/verification/lib.rs&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
757&lt;p&gt;Starting vim with more than one file at the shell prompt populates the arglist. Hit &lt;code&gt;:args&lt;/code&gt; to see the list of files currently ready to edit. The square [brackets] indicate the current file. Navigate through the arglist with &lt;code&gt;:next&lt;/code&gt; and &lt;code&gt;:prev&lt;/code&gt;. I use tpope’s vim-unimpaired &lt;a href="#fn1" class="footnote-ref" id="fnref1" role="doc-noteref"&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;/a&gt;, which adds &lt;code&gt;]a&lt;/code&gt; and &lt;code&gt;[a&lt;/code&gt;, mapped to &lt;code&gt;:next&lt;/code&gt; and &lt;code&gt;:prev&lt;/code&gt;.&lt;/p&gt; 885&lt;p&gt;Starting vim with more than one file at the shell prompt populates the arglist. Hit &lt;code&gt;:args&lt;/code&gt; to see the list of files currently ready to edit. The square [brackets] indicate the current file. Navigate through the arglist with &lt;code&gt;:next&lt;/code&gt; and &lt;code&gt;:prev&lt;/code&gt;. I use tpope’s vim-unimpaired &lt;a href="#fn1" class="footnote-ref" id="fnref1" role="doc-noteref"&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;/a&gt;, which adds &lt;code&gt;]a&lt;/code&gt; and &lt;code&gt;[a&lt;/code&gt;, mapped to &lt;code&gt;:next&lt;/code&gt; and &lt;code&gt;:prev&lt;/code&gt;.&lt;/p&gt;
758&lt;p&gt;All that’s left to do is the find and replace, for which we will be using vim’s &lt;code&gt;argdo&lt;/code&gt;, applying a substitution to every file in the arglist:&lt;/p&gt; 886&lt;p&gt;All that’s left to do is the find and replace, for which we will be using vim’s &lt;code&gt;argdo&lt;/code&gt;, applying a substitution to every file in the arglist:&lt;/p&gt;
759&lt;pre&gt;&lt;code&gt;:argdo s/from_str/from_value/g&lt;/code&gt;&lt;/pre&gt; 887&lt;pre&gt;&lt;code&gt;:argdo s/from_str/from_value/g&lt;/code&gt;&lt;/pre&gt;
@@ -935,26 +1063,26 @@ Reading symbols from main... # yay!&lt;/code&gt;&lt;/pre&gt;
935&lt;p&gt;I chose to write in markdown, and convert to html with &lt;a href="https://kristaps.bsd.lv/lowdown/"&gt;lowdown&lt;/a&gt;.&lt;/p&gt; 1063&lt;p&gt;I chose to write in markdown, and convert to html with &lt;a href="https://kristaps.bsd.lv/lowdown/"&gt;lowdown&lt;/a&gt;.&lt;/p&gt;
936&lt;h3 id="directory-structure"&gt;Directory structure&lt;/h3&gt; 1064&lt;h3 id="directory-structure"&gt;Directory structure&lt;/h3&gt;
937&lt;p&gt;I host my site on GitHub pages, so &lt;code&gt;docs/&lt;/code&gt; has to be the entry point. Markdown formatted posts go into &lt;code&gt;posts/&lt;/code&gt;, get converted into html, and end up in &lt;code&gt;docs/index.html&lt;/code&gt;, something like this:&lt;/p&gt; 1065&lt;p&gt;I host my site on GitHub pages, so &lt;code&gt;docs/&lt;/code&gt; has to be the entry point. Markdown formatted posts go into &lt;code&gt;posts/&lt;/code&gt;, get converted into html, and end up in &lt;code&gt;docs/index.html&lt;/code&gt;, something like this:&lt;/p&gt;
938&lt;div class="sourceCode" id="cb1"&gt;&lt;pre class="sourceCode bash"&gt;&lt;code class="sourceCode bash"&gt;&lt;span id="cb1-1"&gt;&lt;a href="#cb1-1"&gt;&lt;/a&gt;&lt;span class="va"&gt;posts=$(&lt;/span&gt;&lt;span class="fu"&gt;ls&lt;/span&gt; -t ./posts&lt;span class="va"&gt;)&lt;/span&gt; &lt;span class="co"&gt;# chronological order!&lt;/span&gt;&lt;/span&gt; 1066&lt;div class="sourceCode" id="cb1"&gt;&lt;pre class="sourceCode bash"&gt;&lt;code class="sourceCode bash"&gt;&lt;span id="cb1-1"&gt;&lt;a href="#cb1-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="va"&gt;posts=$(&lt;/span&gt;&lt;span class="fu"&gt;ls&lt;/span&gt; -t ./posts&lt;span class="va"&gt;)&lt;/span&gt; # &lt;span class="ex"&gt;chronological&lt;/span&gt; order!&lt;/span&gt;
939&lt;span id="cb1-2"&gt;&lt;a href="#cb1-2"&gt;&lt;/a&gt;&lt;span class="kw"&gt;for&lt;/span&gt; &lt;span class="ex"&gt;f&lt;/span&gt; in &lt;span class="va"&gt;$posts&lt;/span&gt;&lt;span class="kw"&gt;;&lt;/span&gt; &lt;span class="kw"&gt;do&lt;/span&gt;&lt;/span&gt; 1067&lt;span id="cb1-2"&gt;&lt;a href="#cb1-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;for&lt;/span&gt; &lt;span class="ex"&gt;f&lt;/span&gt; in &lt;span class="va"&gt;$posts&lt;/span&gt;&lt;span class="kw"&gt;;&lt;/span&gt; &lt;span class="kw"&gt;do&lt;/span&gt;&lt;/span&gt;
940&lt;span id="cb1-3"&gt;&lt;a href="#cb1-3"&gt;&lt;/a&gt; &lt;span class="va"&gt;file=&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;./posts/&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;$f&lt;/span&gt; &lt;span class="co"&gt;# `ls` mangled our file paths&lt;/span&gt;&lt;/span&gt; 1068&lt;span id="cb1-3"&gt;&lt;a href="#cb1-3" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="va"&gt;file=&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;./posts/&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;$f&lt;/span&gt; # &lt;span class="kw"&gt;`&lt;/span&gt;&lt;span class="fu"&gt;ls&lt;/span&gt;&lt;span class="kw"&gt;`&lt;/span&gt; &lt;span class="ex"&gt;mangled&lt;/span&gt; our file paths&lt;/span&gt;
941&lt;span id="cb1-4"&gt;&lt;a href="#cb1-4"&gt;&lt;/a&gt; &lt;span class="bu"&gt;echo&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;generating post &lt;/span&gt;&lt;span class="va"&gt;$file&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;/span&gt; 1069&lt;span id="cb1-4"&gt;&lt;a href="#cb1-4" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="bu"&gt;echo&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;generating post &lt;/span&gt;&lt;span class="va"&gt;$file&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;/span&gt;
942&lt;span id="cb1-5"&gt;&lt;a href="#cb1-5"&gt;&lt;/a&gt;&lt;/span&gt; 1070&lt;span id="cb1-5"&gt;&lt;a href="#cb1-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
943&lt;span id="cb1-6"&gt;&lt;a href="#cb1-6"&gt;&lt;/a&gt; &lt;span class="va"&gt;html=$(&lt;/span&gt;&lt;span class="ex"&gt;lowdown&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;$file&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;)&lt;/span&gt;&lt;/span&gt; 1071&lt;span id="cb1-6"&gt;&lt;a href="#cb1-6" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="va"&gt;html=$(&lt;/span&gt;&lt;span class="ex"&gt;lowdown&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;$file&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;)&lt;/span&gt;&lt;/span&gt;
944&lt;span id="cb1-7"&gt;&lt;a href="#cb1-7"&gt;&lt;/a&gt; &lt;span class="bu"&gt;echo&lt;/span&gt; -e &lt;span class="st"&gt;&amp;quot;html&amp;quot;&lt;/span&gt; &lt;span class="op"&gt;&amp;gt;&amp;gt;&lt;/span&gt; docs/index.html&lt;/span&gt; 1072&lt;span id="cb1-7"&gt;&lt;a href="#cb1-7" aria-hidden="true"&gt;&lt;/a&gt; &lt;span class="bu"&gt;echo&lt;/span&gt; -e &lt;span class="st"&gt;&amp;quot;html&amp;quot;&lt;/span&gt; &lt;span class="op"&gt;&amp;gt;&amp;gt;&lt;/span&gt; docs/index.html&lt;/span&gt;
945&lt;span id="cb1-8"&gt;&lt;a href="#cb1-8"&gt;&lt;/a&gt;&lt;span class="kw"&gt;done&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 1073&lt;span id="cb1-8"&gt;&lt;a href="#cb1-8" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="kw"&gt;done&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
946&lt;h3 id="assets"&gt;Assets&lt;/h3&gt; 1074&lt;h3 id="assets"&gt;Assets&lt;/h3&gt;
947&lt;p&gt;Most static site generators recommend dropping image assets into the site source itself. That does have it’s merits, but I prefer hosting images separately:&lt;/p&gt; 1075&lt;p&gt;Most static site generators recommend dropping image assets into the site source itself. That does have it’s merits, but I prefer hosting images separately:&lt;/p&gt;
948&lt;div class="sourceCode" id="cb2"&gt;&lt;pre class="sourceCode bash"&gt;&lt;code class="sourceCode bash"&gt;&lt;span id="cb2-1"&gt;&lt;a href="#cb2-1"&gt;&lt;/a&gt;&lt;span class="co"&gt;# strip file extension&lt;/span&gt;&lt;/span&gt; 1076&lt;div class="sourceCode" id="cb2"&gt;&lt;pre class="sourceCode bash"&gt;&lt;code class="sourceCode bash"&gt;&lt;span id="cb2-1"&gt;&lt;a href="#cb2-1" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;# strip file extension&lt;/span&gt;&lt;/span&gt;
949&lt;span id="cb2-2"&gt;&lt;a href="#cb2-2"&gt;&lt;/a&gt;&lt;span class="va"&gt;ext=&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;${1##&lt;/span&gt;*.&lt;span class="va"&gt;}&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;/span&gt; 1077&lt;span id="cb2-2"&gt;&lt;a href="#cb2-2" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="va"&gt;ext=&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;${1##&lt;/span&gt;*.&lt;span class="va"&gt;}&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;/span&gt;
950&lt;span id="cb2-3"&gt;&lt;a href="#cb2-3"&gt;&lt;/a&gt;&lt;/span&gt; 1078&lt;span id="cb2-3"&gt;&lt;a href="#cb2-3" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
951&lt;span id="cb2-4"&gt;&lt;a href="#cb2-4"&gt;&lt;/a&gt;&lt;span class="co"&gt;# generate a random file name&lt;/span&gt;&lt;/span&gt; 1079&lt;span id="cb2-4"&gt;&lt;a href="#cb2-4" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;# generate a random file name&lt;/span&gt;&lt;/span&gt;
952&lt;span id="cb2-5"&gt;&lt;a href="#cb2-5"&gt;&lt;/a&gt;&lt;span class="va"&gt;id=$(&lt;/span&gt; &lt;span class="fu"&gt;cat&lt;/span&gt; /dev/urandom &lt;span class="kw"&gt;|&lt;/span&gt; &lt;span class="fu"&gt;tr&lt;/span&gt; -dc &lt;span class="st"&gt;&amp;#39;a-zA-Z0-9&amp;#39;&lt;/span&gt; &lt;span class="kw"&gt;|&lt;/span&gt; &lt;span class="ex"&gt;fold&lt;/span&gt; -w 2 &lt;span class="kw"&gt;|&lt;/span&gt; &lt;span class="fu"&gt;head&lt;/span&gt; -n 1 &lt;span class="va"&gt;)&lt;/span&gt;&lt;/span&gt; 1080&lt;span id="cb2-5"&gt;&lt;a href="#cb2-5" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="va"&gt;id=$(&lt;/span&gt; &lt;span class="fu"&gt;cat&lt;/span&gt; /dev/urandom &lt;span class="kw"&gt;|&lt;/span&gt; &lt;span class="fu"&gt;tr&lt;/span&gt; -dc &lt;span class="st"&gt;&amp;#39;a-zA-Z0-9&amp;#39;&lt;/span&gt; &lt;span class="kw"&gt;|&lt;/span&gt; &lt;span class="ex"&gt;fold&lt;/span&gt; -w 2 &lt;span class="kw"&gt;|&lt;/span&gt; &lt;span class="fu"&gt;head&lt;/span&gt; -n 1 &lt;span class="va"&gt;)&lt;/span&gt;&lt;/span&gt;
953&lt;span id="cb2-6"&gt;&lt;a href="#cb2-6"&gt;&lt;/a&gt;&lt;span class="va"&gt;id=&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;$id&lt;/span&gt;&lt;span class="st"&gt;.&lt;/span&gt;&lt;span class="va"&gt;$ext&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;/span&gt; 1081&lt;span id="cb2-6"&gt;&lt;a href="#cb2-6" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="va"&gt;id=&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;$id&lt;/span&gt;&lt;span class="st"&gt;.&lt;/span&gt;&lt;span class="va"&gt;$ext&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;/span&gt;
954&lt;span id="cb2-7"&gt;&lt;a href="#cb2-7"&gt;&lt;/a&gt;&lt;/span&gt; 1082&lt;span id="cb2-7"&gt;&lt;a href="#cb2-7" aria-hidden="true"&gt;&lt;/a&gt;&lt;/span&gt;
955&lt;span id="cb2-8"&gt;&lt;a href="#cb2-8"&gt;&lt;/a&gt;&lt;span class="co"&gt;# copy to my file host&lt;/span&gt;&lt;/span&gt; 1083&lt;span id="cb2-8"&gt;&lt;a href="#cb2-8" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="co"&gt;# copy to my file host&lt;/span&gt;&lt;/span&gt;
956&lt;span id="cb2-9"&gt;&lt;a href="#cb2-9"&gt;&lt;/a&gt;&lt;span class="fu"&gt;scp&lt;/span&gt; -P 443 &lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;$1&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt; emerald:files/&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;$id&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt; &lt;/span&gt; 1084&lt;span id="cb2-9"&gt;&lt;a href="#cb2-9" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="fu"&gt;scp&lt;/span&gt; -P 443 &lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;$1&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt; emerald:files/&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;span class="va"&gt;$id&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt; &lt;/span&gt;
957&lt;span id="cb2-10"&gt;&lt;a href="#cb2-10"&gt;&lt;/a&gt;&lt;span class="bu"&gt;echo&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;https://u.peppe.rs/&lt;/span&gt;&lt;span class="va"&gt;$id&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt; 1085&lt;span id="cb2-10"&gt;&lt;a href="#cb2-10" aria-hidden="true"&gt;&lt;/a&gt;&lt;span class="bu"&gt;echo&lt;/span&gt; &lt;span class="st"&gt;&amp;quot;https://u.peppe.rs/&lt;/span&gt;&lt;span class="va"&gt;$id&lt;/span&gt;&lt;span class="st"&gt;&amp;quot;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;
958&lt;h3 id="templating"&gt;Templating&lt;/h3&gt; 1086&lt;h3 id="templating"&gt;Templating&lt;/h3&gt;
959&lt;p&gt;&lt;a href="https://github.com/NerdyPepper/site/blob/master/generate.sh"&gt;&lt;code&gt;generate.sh&lt;/code&gt;&lt;/a&gt; brings the above bits and pieces together (with some extra cruft to avoid javascript). It uses &lt;code&gt;sed&lt;/code&gt; to produce nice titles from the file names (removes underscores, title-case), and &lt;code&gt;date(1)&lt;/code&gt; to add the date to each post listing!&lt;/p&gt;</description> 1087&lt;p&gt;&lt;a href="https://github.com/NerdyPepper/site/blob/master/generate.sh"&gt;&lt;code&gt;generate.sh&lt;/code&gt;&lt;/a&gt; brings the above bits and pieces together (with some extra cruft to avoid javascript). It uses &lt;code&gt;sed&lt;/code&gt; to produce nice titles from the file names (removes underscores, title-case), and &lt;code&gt;date(1)&lt;/code&gt; to add the date to each post listing!&lt;/p&gt;</description>
960<link>https://peppe.rs/posts/static_sites_with_bash/</link> 1088<link>https://peppe.rs/posts/static_sites_with_bash/</link>
diff --git a/docs/posts/WPA_woes/index.html b/docs/posts/WPA_woes/index.html
index 5121434..4feb244 100644
--- a/docs/posts/WPA_woes/index.html
+++ b/docs/posts/WPA_woes/index.html
@@ -74,7 +74,10 @@ $ sudo sv restart dhcpcd</code></pre>
74 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 74 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
75 <p> 75 <p>
76 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 76 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
77 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 77 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
78 I also design fonts:
79 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
80 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
78 </p> 81 </p>
79 <p>Send me a mail at [email protected] or a message at [email protected].</p> 82 <p>Send me a mail at [email protected] or a message at [email protected].</p>
80 </div> 83 </div>
diff --git a/docs/posts/auto-currying_rust_functions/index.html b/docs/posts/auto-currying_rust_functions/index.html
index 99cb9af..1a56697 100644
--- a/docs/posts/auto-currying_rust_functions/index.html
+++ b/docs/posts/auto-currying_rust_functions/index.html
@@ -94,17 +94,17 @@ h(x)(y)(z) = g(y)(z) = k(z) = v</code></pre>
94<p>We will be using Attribute macros to convert a Rust function into a curried Rust function, which we should be able to call via: <code>function(arg1)(arg2)</code>.</p> 94<p>We will be using Attribute macros to convert a Rust function into a curried Rust function, which we should be able to call via: <code>function(arg1)(arg2)</code>.</p>
95<h3 id="definitions">Definitions</h3> 95<h3 id="definitions">Definitions</h3>
96<p>Being respectable programmers, we define the input to and the output from our proc-macro. Here’s a good non-trivial function to start out with:</p> 96<p>Being respectable programmers, we define the input to and the output from our proc-macro. Here’s a good non-trivial function to start out with:</p>
97<div class="sourceCode" id="cb4"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb4-1"><a href="#cb4-1"></a><span class="kw">fn</span> add(x: <span class="dt">u32</span>, y: <span class="dt">u32</span>, z: <span class="dt">u32</span>) -&gt; <span class="dt">u32</span> <span class="op">{</span></span> 97<div class="sourceCode" id="cb4"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true"></a><span class="kw">fn</span> add(x<span class="op">:</span> <span class="dt">u32</span><span class="op">,</span> y<span class="op">:</span> <span class="dt">u32</span><span class="op">,</span> z<span class="op">:</span> <span class="dt">u32</span>) <span class="op">-&gt;</span> <span class="dt">u32</span> <span class="op">{</span></span>
98<span id="cb4-2"><a href="#cb4-2"></a> <span class="kw">return</span> x + y + z;</span> 98<span id="cb4-2"><a href="#cb4-2" aria-hidden="true"></a> <span class="kw">return</span> x <span class="op">+</span> y <span class="op">+</span> z<span class="op">;</span></span>
99<span id="cb4-3"><a href="#cb4-3"></a><span class="op">}</span></span></code></pre></div> 99<span id="cb4-3"><a href="#cb4-3" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
100<p>Hmm, what would our output look like? What should our proc-macro generate ideally? Well, if we understood currying correctly, we should accept an argument and return a function that accepts an argument and returns … you get the point. Something like this should do:</p> 100<p>Hmm, what would our output look like? What should our proc-macro generate ideally? Well, if we understood currying correctly, we should accept an argument and return a function that accepts an argument and returns … you get the point. Something like this should do:</p>
101<div class="sourceCode" id="cb5"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb5-1"><a href="#cb5-1"></a><span class="kw">fn</span> add_curried1(x: <span class="dt">u32</span>) -&gt; ? <span class="op">{</span></span> 101<div class="sourceCode" id="cb5"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true"></a><span class="kw">fn</span> add_curried1(x<span class="op">:</span> <span class="dt">u32</span>) <span class="op">-&gt;</span> <span class="op">?</span> <span class="op">{</span></span>
102<span id="cb5-2"><a href="#cb5-2"></a> <span class="kw">return</span> <span class="kw">fn</span> add_curried2 (y: <span class="dt">u32</span>) -&gt; ? <span class="op">{</span></span> 102<span id="cb5-2"><a href="#cb5-2" aria-hidden="true"></a> <span class="kw">return</span> <span class="kw">fn</span> add_curried2 (y<span class="op">:</span> <span class="dt">u32</span>) <span class="op">-&gt;</span> <span class="op">?</span> <span class="op">{</span></span>
103<span id="cb5-3"><a href="#cb5-3"></a> <span class="kw">return</span> <span class="kw">fn</span> add_curried3 (z: <span class="dt">u32</span>) -&gt; <span class="dt">u32</span> <span class="op">{</span></span> 103<span id="cb5-3"><a href="#cb5-3" aria-hidden="true"></a> <span class="kw">return</span> <span class="kw">fn</span> add_curried3 (z<span class="op">:</span> <span class="dt">u32</span>) <span class="op">-&gt;</span> <span class="dt">u32</span> <span class="op">{</span></span>
104<span id="cb5-4"><a href="#cb5-4"></a> <span class="kw">return</span> x + y + z;</span> 104<span id="cb5-4"><a href="#cb5-4" aria-hidden="true"></a> <span class="kw">return</span> x <span class="op">+</span> y <span class="op">+</span> z<span class="op">;</span></span>
105<span id="cb5-5"><a href="#cb5-5"></a> <span class="op">}</span></span> 105<span id="cb5-5"><a href="#cb5-5" aria-hidden="true"></a> <span class="op">}</span></span>
106<span id="cb5-6"><a href="#cb5-6"></a> <span class="op">}</span></span> 106<span id="cb5-6"><a href="#cb5-6" aria-hidden="true"></a> <span class="op">}</span></span>
107<span id="cb5-7"><a href="#cb5-7"></a><span class="op">}</span></span></code></pre></div> 107<span id="cb5-7"><a href="#cb5-7" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
108<p>A couple of things to note:</p> 108<p>A couple of things to note:</p>
109<p><strong>Return types</strong><br /> 109<p><strong>Return types</strong><br />
110We have placed <code>?</code>s in place of return types. Let’s try to fix that. <code>add_curried3</code> returns the ‘value’, so <code>u32</code> is accurate. <code>add_curried2</code> returns <code>add_curried3</code>. What is the type of <code>add_curried3</code>? It is a function that takes in a <code>u32</code> and returns a <code>u32</code>. So a <code>fn(u32) -&gt; u32</code> will do right? No, I’ll explain why in the next point, but for now, we will make use of the <code>Fn</code> trait, our return type is <code>impl Fn(u32) -&gt; u32</code>. This basically tells the compiler that we will be returning something function-like, a.k.a, behaves like a <code>Fn</code>. Cool!</p> 110We have placed <code>?</code>s in place of return types. Let’s try to fix that. <code>add_curried3</code> returns the ‘value’, so <code>u32</code> is accurate. <code>add_curried2</code> returns <code>add_curried3</code>. What is the type of <code>add_curried3</code>? It is a function that takes in a <code>u32</code> and returns a <code>u32</code>. So a <code>fn(u32) -&gt; u32</code> will do right? No, I’ll explain why in the next point, but for now, we will make use of the <code>Fn</code> trait, our return type is <code>impl Fn(u32) -&gt; u32</code>. This basically tells the compiler that we will be returning something function-like, a.k.a, behaves like a <code>Fn</code>. Cool!</p>
@@ -117,9 +117,9 @@ We have placed <code>?</code>s in place of return types. Let’s try to fix that
117A function cannot access it’s environment. Our solution will not work. <code>add_curried3</code> attempts to access <code>x</code>, which is not allowed! A closure<a href="#fn1" class="footnote-ref" id="fnref1" role="doc-noteref"><sup>1</sup></a> however, can. If we are returning a closure, our return type must be <code>impl Fn</code>, and not <code>fn</code>. The difference between the <code>Fn</code> trait and function pointers is beyond the scope of this post.</p> 117A function cannot access it’s environment. Our solution will not work. <code>add_curried3</code> attempts to access <code>x</code>, which is not allowed! A closure<a href="#fn1" class="footnote-ref" id="fnref1" role="doc-noteref"><sup>1</sup></a> however, can. If we are returning a closure, our return type must be <code>impl Fn</code>, and not <code>fn</code>. The difference between the <code>Fn</code> trait and function pointers is beyond the scope of this post.</p>
118<h3 id="refinement">Refinement</h3> 118<h3 id="refinement">Refinement</h3>
119<p>Armed with knowledge, we refine our expected output, this time, employing closures:</p> 119<p>Armed with knowledge, we refine our expected output, this time, employing closures:</p>
120<div class="sourceCode" id="cb8"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb8-1"><a href="#cb8-1"></a><span class="kw">fn</span> add(x: <span class="dt">u32</span>) -&gt; <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; <span class="dt">u32</span> <span class="op">{</span></span> 120<div class="sourceCode" id="cb8"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true"></a><span class="kw">fn</span> add(x<span class="op">:</span> <span class="dt">u32</span>) <span class="op">-&gt;</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> <span class="dt">u32</span> <span class="op">{</span></span>
121<span id="cb8-2"><a href="#cb8-2"></a> <span class="kw">return</span> <span class="kw">move</span> |y| <span class="kw">move</span> |z| x + y + z;</span> 121<span id="cb8-2"><a href="#cb8-2" aria-hidden="true"></a> <span class="kw">return</span> <span class="kw">move</span> <span class="op">|</span>y<span class="op">|</span> <span class="kw">move</span> <span class="op">|</span>z<span class="op">|</span> x <span class="op">+</span> y <span class="op">+</span> z<span class="op">;</span></span>
122<span id="cb8-3"><a href="#cb8-3"></a><span class="op">}</span></span></code></pre></div> 122<span id="cb8-3"><a href="#cb8-3" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
123<p>Alas, that does not compile either! It errors out with the following message:</p> 123<p>Alas, that does not compile either! It errors out with the following message:</p>
124<pre><code>error[E0562]: `impl Trait` not allowed outside of function 124<pre><code>error[E0562]: `impl Trait` not allowed outside of function
125and inherent method return types 125and inherent method return types
@@ -130,15 +130,15 @@ and inherent method return types
130</code></pre> 130</code></pre>
131<p>You are allowed to return an <code>impl Fn</code> only inside a function. We are currently returning it from another return! Or at least, that was the most I could make out of the error message.</p> 131<p>You are allowed to return an <code>impl Fn</code> only inside a function. We are currently returning it from another return! Or at least, that was the most I could make out of the error message.</p>
132<p>We are going to have to cheat a bit to fix this issue; with type aliases and a convenient nightly feature <a href="#fn2" class="footnote-ref" id="fnref2" role="doc-noteref"><sup>2</sup></a>:</p> 132<p>We are going to have to cheat a bit to fix this issue; with type aliases and a convenient nightly feature <a href="#fn2" class="footnote-ref" id="fnref2" role="doc-noteref"><sup>2</sup></a>:</p>
133<div class="sourceCode" id="cb10"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb10-1"><a href="#cb10-1"></a><span class="at">#![</span>feature<span class="at">(</span>type_alias_impl_trait<span class="at">)]</span> <span class="co">// allows us to use `impl Fn` in type aliases!</span></span> 133<div class="sourceCode" id="cb10"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true"></a><span class="at">#![</span>feature<span class="at">(</span>type_alias_impl_trait<span class="at">)]</span> <span class="co">// allows us to use `impl Fn` in type aliases!</span></span>
134<span id="cb10-2"><a href="#cb10-2"></a></span> 134<span id="cb10-2"><a href="#cb10-2" aria-hidden="true"></a></span>
135<span id="cb10-3"><a href="#cb10-3"></a><span class="kw">type</span> T0 = <span class="dt">u32</span>; <span class="co">// the return value when zero args are to be applied</span></span> 135<span id="cb10-3"><a href="#cb10-3" aria-hidden="true"></a><span class="kw">type</span> T0 <span class="op">=</span> <span class="dt">u32</span><span class="op">;</span> <span class="co">// the return value when zero args are to be applied</span></span>
136<span id="cb10-4"><a href="#cb10-4"></a><span class="kw">type</span> T1 = <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; T0; <span class="co">// the return value when one arg is to be applied</span></span> 136<span id="cb10-4"><a href="#cb10-4" aria-hidden="true"></a><span class="kw">type</span> T1 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> T0<span class="op">;</span> <span class="co">// the return value when one arg is to be applied</span></span>
137<span id="cb10-5"><a href="#cb10-5"></a><span class="kw">type</span> T2 = <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; T1; <span class="co">// the return value when two args are to be applied</span></span> 137<span id="cb10-5"><a href="#cb10-5" aria-hidden="true"></a><span class="kw">type</span> T2 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> T1<span class="op">;</span> <span class="co">// the return value when two args are to be applied</span></span>
138<span id="cb10-6"><a href="#cb10-6"></a></span> 138<span id="cb10-6"><a href="#cb10-6" aria-hidden="true"></a></span>
139<span id="cb10-7"><a href="#cb10-7"></a><span class="kw">fn</span> add(x: <span class="dt">u32</span>) -&gt; T2 <span class="op">{</span></span> 139<span id="cb10-7"><a href="#cb10-7" aria-hidden="true"></a><span class="kw">fn</span> add(x<span class="op">:</span> <span class="dt">u32</span>) <span class="op">-&gt;</span> T2 <span class="op">{</span></span>
140<span id="cb10-8"><a href="#cb10-8"></a> <span class="kw">return</span> <span class="kw">move</span> |y| <span class="kw">move</span> |z| x + y + z;</span> 140<span id="cb10-8"><a href="#cb10-8" aria-hidden="true"></a> <span class="kw">return</span> <span class="kw">move</span> <span class="op">|</span>y<span class="op">|</span> <span class="kw">move</span> <span class="op">|</span>z<span class="op">|</span> x <span class="op">+</span> y <span class="op">+</span> z<span class="op">;</span></span>
141<span id="cb10-9"><a href="#cb10-9"></a><span class="op">}</span></span></code></pre></div> 141<span id="cb10-9"><a href="#cb10-9" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
142<p>Drop that into a cargo project, call <code>add(4)(5)(6)</code>, cross your fingers, and run <code>cargo +nightly run</code>. You should see a 15 unless you forgot to print it!</p> 142<p>Drop that into a cargo project, call <code>add(4)(5)(6)</code>, cross your fingers, and run <code>cargo +nightly run</code>. You should see a 15 unless you forgot to print it!</p>
143<h3 id="the-in-betweens">The In-Betweens</h3> 143<h3 id="the-in-betweens">The In-Betweens</h3>
144<p>Let us write the magical bits that take us from function to curried function.</p> 144<p>Let us write the magical bits that take us from function to curried function.</p>
@@ -172,19 +172,19 @@ proc-macro = true # this is important!</code></pre>
172<p>We will be using an external <code>proc-macro2</code> crate as well as an internal <code>proc-macro</code> crate. Not confusing at all!</p> 172<p>We will be using an external <code>proc-macro2</code> crate as well as an internal <code>proc-macro</code> crate. Not confusing at all!</p>
173<h4 id="the-attribute-macro">The attribute macro</h4> 173<h4 id="the-attribute-macro">The attribute macro</h4>
174<p>Drop this into <code>src/lib.rs</code>, to get the ball rolling.</p> 174<p>Drop this into <code>src/lib.rs</code>, to get the ball rolling.</p>
175<div class="sourceCode" id="cb13"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb13-1"><a href="#cb13-1"></a><span class="co">// src/lib.rs</span></span> 175<div class="sourceCode" id="cb13"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true"></a><span class="co">// src/lib.rs</span></span>
176<span id="cb13-2"><a href="#cb13-2"></a></span> 176<span id="cb13-2"><a href="#cb13-2" aria-hidden="true"></a></span>
177<span id="cb13-3"><a href="#cb13-3"></a><span class="kw">use</span> <span class="pp">proc_macro::</span>TokenStream; <span class="co">// 1</span></span> 177<span id="cb13-3"><a href="#cb13-3" aria-hidden="true"></a><span class="kw">use</span> <span class="pp">proc_macro::</span>TokenStream<span class="op">;</span> <span class="co">// 1</span></span>
178<span id="cb13-4"><a href="#cb13-4"></a><span class="kw">use</span> <span class="pp">quote::</span>quote;</span> 178<span id="cb13-4"><a href="#cb13-4" aria-hidden="true"></a><span class="kw">use</span> <span class="pp">quote::</span>quote<span class="op">;</span></span>
179<span id="cb13-5"><a href="#cb13-5"></a><span class="kw">use</span> <span class="pp">syn::</span><span class="op">{</span>parse_macro_input, ItemFn<span class="op">}</span>;</span> 179<span id="cb13-5"><a href="#cb13-5" aria-hidden="true"></a><span class="kw">use</span> <span class="pp">syn::</span><span class="op">{</span>parse_macro_input<span class="op">,</span> ItemFn<span class="op">};</span></span>
180<span id="cb13-6"><a href="#cb13-6"></a></span> 180<span id="cb13-6"><a href="#cb13-6" aria-hidden="true"></a></span>
181<span id="cb13-7"><a href="#cb13-7"></a><span class="at">#[</span>proc_macro_attribute<span class="at">]</span> <span class="co">// 2</span></span> 181<span id="cb13-7"><a href="#cb13-7" aria-hidden="true"></a><span class="at">#[</span>proc_macro_attribute<span class="at">]</span> <span class="co">// 2</span></span>
182<span id="cb13-8"><a href="#cb13-8"></a><span class="kw">pub</span> <span class="kw">fn</span> curry(_attr: TokenStream, item: TokenStream) -&gt; TokenStream <span class="op">{</span></span> 182<span id="cb13-8"><a href="#cb13-8" aria-hidden="true"></a><span class="kw">pub</span> <span class="kw">fn</span> curry(_attr<span class="op">:</span> TokenStream<span class="op">,</span> item<span class="op">:</span> TokenStream) <span class="op">-&gt;</span> TokenStream <span class="op">{</span></span>
183<span id="cb13-9"><a href="#cb13-9"></a> <span class="kw">let</span> parsed = <span class="pp">parse_macro_input!</span>(item <span class="kw">as</span> ItemFn); <span class="co">// 3</span></span> 183<span id="cb13-9"><a href="#cb13-9" aria-hidden="true"></a> <span class="kw">let</span> parsed <span class="op">=</span> <span class="pp">parse_macro_input!</span>(item <span class="kw">as</span> ItemFn)<span class="op">;</span> <span class="co">// 3</span></span>
184<span id="cb13-10"><a href="#cb13-10"></a> generate_curry(parsed).into() <span class="co">// 4</span></span> 184<span id="cb13-10"><a href="#cb13-10" aria-hidden="true"></a> generate_curry(parsed)<span class="op">.</span>into() <span class="co">// 4</span></span>
185<span id="cb13-11"><a href="#cb13-11"></a><span class="op">}</span></span> 185<span id="cb13-11"><a href="#cb13-11" aria-hidden="true"></a><span class="op">}</span></span>
186<span id="cb13-12"><a href="#cb13-12"></a></span> 186<span id="cb13-12"><a href="#cb13-12" aria-hidden="true"></a></span>
187<span id="cb13-13"><a href="#cb13-13"></a><span class="kw">fn</span> generate_curry(parsed: ItemFn) -&gt; <span class="pp">proc_macro2::</span>TokenStream <span class="op">{}</span></span></code></pre></div> 187<span id="cb13-13"><a href="#cb13-13" aria-hidden="true"></a><span class="kw">fn</span> generate_curry(parsed<span class="op">:</span> ItemFn) <span class="op">-&gt;</span> <span class="pp">proc_macro2::</span>TokenStream <span class="op">{}</span></span></code></pre></div>
188<p><strong>1. Imports</strong></p> 188<p><strong>1. Imports</strong></p>
189<p>A <code>Tokenstream</code> holds (hopefully valid) Rust code, this is the type of our input and output. Note that we are importing this type from <code>proc_macro</code> and not <code>proc_macro2</code>.</p> 189<p>A <code>Tokenstream</code> holds (hopefully valid) Rust code, this is the type of our input and output. Note that we are importing this type from <code>proc_macro</code> and not <code>proc_macro2</code>.</p>
190<p><code>quote!</code> from the <code>quote</code> crate is a macro that allows us to quickly produce <code>TokenStream</code>s. Much like the LISP <code>quote</code> procedure, you can use the <code>quote!</code> macro for symbolic transformations.</p> 190<p><code>quote!</code> from the <code>quote</code> crate is a macro that allows us to quickly produce <code>TokenStream</code>s. Much like the LISP <code>quote</code> procedure, you can use the <code>quote!</code> macro for symbolic transformations.</p>
@@ -196,16 +196,16 @@ proc-macro = true # this is important!</code></pre>
196<p><strong>4. Returning <code>TokenStream</code>s </strong></p> 196<p><strong>4. Returning <code>TokenStream</code>s </strong></p>
197<p>We haven’t filled in <code>generate_curry</code> yet, but we can see that it returns a <code>proc_macro2::TokenStream</code> and not a <code>proc_macro::TokenStream</code>, so drop a <code>.into()</code> to convert it.</p> 197<p>We haven’t filled in <code>generate_curry</code> yet, but we can see that it returns a <code>proc_macro2::TokenStream</code> and not a <code>proc_macro::TokenStream</code>, so drop a <code>.into()</code> to convert it.</p>
198<p>Lets move on, and fill in <code>generate_curry</code>, I would suggest keeping the documentation for <a href="https://docs.rs/syn/1.0.19/syn/struct.ItemFn.html"><code>syn::ItemFn</code></a> and <a href="https://docs.rs/syn/1.0.19/syn/struct.Signature.html"><code>syn::Signature</code></a> open.</p> 198<p>Lets move on, and fill in <code>generate_curry</code>, I would suggest keeping the documentation for <a href="https://docs.rs/syn/1.0.19/syn/struct.ItemFn.html"><code>syn::ItemFn</code></a> and <a href="https://docs.rs/syn/1.0.19/syn/struct.Signature.html"><code>syn::Signature</code></a> open.</p>
199<div class="sourceCode" id="cb14"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb14-1"><a href="#cb14-1"></a><span class="co">// src/lib.rs</span></span> 199<div class="sourceCode" id="cb14"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true"></a><span class="co">// src/lib.rs</span></span>
200<span id="cb14-2"><a href="#cb14-2"></a></span> 200<span id="cb14-2"><a href="#cb14-2" aria-hidden="true"></a></span>
201<span id="cb14-3"><a href="#cb14-3"></a><span class="kw">fn</span> generate_curry(parsed: ItemFn) -&gt; <span class="pp">proc_macro2::</span>TokenStream <span class="op">{</span></span> 201<span id="cb14-3"><a href="#cb14-3" aria-hidden="true"></a><span class="kw">fn</span> generate_curry(parsed<span class="op">:</span> ItemFn) <span class="op">-&gt;</span> <span class="pp">proc_macro2::</span>TokenStream <span class="op">{</span></span>
202<span id="cb14-4"><a href="#cb14-4"></a> <span class="kw">let</span> fn_body = parsed.block; <span class="co">// function body</span></span> 202<span id="cb14-4"><a href="#cb14-4" aria-hidden="true"></a> <span class="kw">let</span> fn_body <span class="op">=</span> parsed<span class="op">.</span>block<span class="op">;</span> <span class="co">// function body</span></span>
203<span id="cb14-5"><a href="#cb14-5"></a> <span class="kw">let</span> sig = parsed.sig; <span class="co">// function signature</span></span> 203<span id="cb14-5"><a href="#cb14-5" aria-hidden="true"></a> <span class="kw">let</span> sig <span class="op">=</span> parsed<span class="op">.</span>sig<span class="op">;</span> <span class="co">// function signature</span></span>
204<span id="cb14-6"><a href="#cb14-6"></a> <span class="kw">let</span> vis = parsed.vis; <span class="co">// visibility, pub or not</span></span> 204<span id="cb14-6"><a href="#cb14-6" aria-hidden="true"></a> <span class="kw">let</span> vis <span class="op">=</span> parsed<span class="op">.</span>vis<span class="op">;</span> <span class="co">// visibility, pub or not</span></span>
205<span id="cb14-7"><a href="#cb14-7"></a> <span class="kw">let</span> fn_name = sig.ident; <span class="co">// function name/identifier</span></span> 205<span id="cb14-7"><a href="#cb14-7" aria-hidden="true"></a> <span class="kw">let</span> fn_name <span class="op">=</span> sig<span class="op">.</span>ident<span class="op">;</span> <span class="co">// function name/identifier</span></span>
206<span id="cb14-8"><a href="#cb14-8"></a> <span class="kw">let</span> fn_args = sig.inputs; <span class="co">// comma separated args</span></span> 206<span id="cb14-8"><a href="#cb14-8" aria-hidden="true"></a> <span class="kw">let</span> fn_args <span class="op">=</span> sig<span class="op">.</span>inputs<span class="op">;</span> <span class="co">// comma separated args</span></span>
207<span id="cb14-9"><a href="#cb14-9"></a> <span class="kw">let</span> fn_return_type = sig.output; <span class="co">// return type</span></span> 207<span id="cb14-9"><a href="#cb14-9" aria-hidden="true"></a> <span class="kw">let</span> fn_return_type <span class="op">=</span> sig<span class="op">.</span>output<span class="op">;</span> <span class="co">// return type</span></span>
208<span id="cb14-10"><a href="#cb14-10"></a><span class="op">}</span></span></code></pre></div> 208<span id="cb14-10"><a href="#cb14-10" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
209<p>We are simply extracting the bits of the function, we will be reusing the original function’s visibility and name. Take a look at what <code>syn::Signature</code> can tell us about a function:</p> 209<p>We are simply extracting the bits of the function, we will be reusing the original function’s visibility and name. Take a look at what <code>syn::Signature</code> can tell us about a function:</p>
210<pre><code> .-- syn::Ident (ident) 210<pre><code> .-- syn::Ident (ident)
211 / 211 /
@@ -217,220 +217,220 @@ syn::token::Fn --&#39; / \ (output)
217<p>Enough analysis, lets produce our first bit of Rust code.</p> 217<p>Enough analysis, lets produce our first bit of Rust code.</p>
218<h4 id="function-body">Function Body</h4> 218<h4 id="function-body">Function Body</h4>
219<p>Recall that the body of a curried <code>add</code> should look like this:</p> 219<p>Recall that the body of a curried <code>add</code> should look like this:</p>
220<div class="sourceCode" id="cb16"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb16-1"><a href="#cb16-1"></a><span class="kw">return</span> <span class="kw">move</span> |y| <span class="kw">move</span> |z| x + y + z;</span></code></pre></div> 220<div class="sourceCode" id="cb16"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true"></a><span class="kw">return</span> <span class="kw">move</span> <span class="op">|</span>y<span class="op">|</span> <span class="kw">move</span> <span class="op">|</span>z<span class="op">|</span> x <span class="op">+</span> y <span class="op">+</span> z<span class="op">;</span></span></code></pre></div>
221<p>And in general:</p> 221<p>And in general:</p>
222<div class="sourceCode" id="cb17"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb17-1"><a href="#cb17-1"></a><span class="kw">return</span> <span class="kw">move</span> |arg2| <span class="kw">move</span> |arg3| ... |argN| &lt;function body here&gt;</span></code></pre></div> 222<div class="sourceCode" id="cb17"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true"></a><span class="kw">return</span> <span class="kw">move</span> <span class="op">|</span>arg2<span class="op">|</span> <span class="kw">move</span> <span class="op">|</span>arg3<span class="op">|</span> <span class="op">...</span> <span class="op">|</span>argN<span class="op">|</span> <span class="op">&lt;</span>function body here<span class="op">&gt;</span></span></code></pre></div>
223<p>We already have the function’s body, provided by <code>fn_body</code>, in our <code>generate_curry</code> function. All that’s left to add is the <code>move |arg2| move |arg3| ...</code> stuff, for which we need to extract the argument identifiers (doc: <a href="https://docs.rs/syn/1.0.18/syn/punctuated/struct.Punctuated.html">Punctuated</a>, <a href="https://docs.rs/syn/1.0.18/syn/enum.FnArg.html">FnArg</a>, <a href="https://docs.rs/syn/1.0.18/syn/struct.PatType.html">PatType</a>):</p> 223<p>We already have the function’s body, provided by <code>fn_body</code>, in our <code>generate_curry</code> function. All that’s left to add is the <code>move |arg2| move |arg3| ...</code> stuff, for which we need to extract the argument identifiers (doc: <a href="https://docs.rs/syn/1.0.18/syn/punctuated/struct.Punctuated.html">Punctuated</a>, <a href="https://docs.rs/syn/1.0.18/syn/enum.FnArg.html">FnArg</a>, <a href="https://docs.rs/syn/1.0.18/syn/struct.PatType.html">PatType</a>):</p>
224<div class="sourceCode" id="cb18"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb18-1"><a href="#cb18-1"></a><span class="co">// src/lib.rs</span></span> 224<div class="sourceCode" id="cb18"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true"></a><span class="co">// src/lib.rs</span></span>
225<span id="cb18-2"><a href="#cb18-2"></a><span class="kw">use</span> <span class="pp">syn::punctuated::</span>Punctuated;</span> 225<span id="cb18-2"><a href="#cb18-2" aria-hidden="true"></a><span class="kw">use</span> <span class="pp">syn::punctuated::</span>Punctuated<span class="op">;</span></span>
226<span id="cb18-3"><a href="#cb18-3"></a><span class="kw">use</span> <span class="pp">syn::</span><span class="op">{</span>parse_macro_input, FnArg, Pat, ItemFn, Block<span class="op">}</span>;</span> 226<span id="cb18-3"><a href="#cb18-3" aria-hidden="true"></a><span class="kw">use</span> <span class="pp">syn::</span><span class="op">{</span>parse_macro_input<span class="op">,</span> FnArg<span class="op">,</span> Pat<span class="op">,</span> ItemFn<span class="op">,</span> Block<span class="op">};</span></span>
227<span id="cb18-4"><a href="#cb18-4"></a></span> 227<span id="cb18-4"><a href="#cb18-4" aria-hidden="true"></a></span>
228<span id="cb18-5"><a href="#cb18-5"></a><span class="kw">fn</span> extract_arg_idents(fn_args: Punctuated&lt;FnArg, <span class="pp">syn::token::</span>Comma&gt;) -&gt; <span class="dt">Vec</span>&lt;<span class="dt">Box</span>&lt;Pat&gt;&gt; <span class="op">{</span> </span> 228<span id="cb18-5"><a href="#cb18-5" aria-hidden="true"></a><span class="kw">fn</span> extract_arg_idents(fn_args<span class="op">:</span> Punctuated<span class="op">&lt;</span>FnArg<span class="op">,</span> <span class="pp">syn::token::</span>Comma<span class="op">&gt;</span>) <span class="op">-&gt;</span> <span class="dt">Vec</span><span class="op">&lt;</span><span class="dt">Box</span><span class="op">&lt;</span>Pat<span class="op">&gt;&gt;</span> <span class="op">{</span> </span>
229<span id="cb18-6"><a href="#cb18-6"></a> <span class="kw">return</span> fn_args.into_iter().map(extract_arg_pat).<span class="pp">collect::</span>&lt;<span class="dt">Vec</span>&lt;_&gt;&gt;();</span> 229<span id="cb18-6"><a href="#cb18-6" aria-hidden="true"></a> <span class="kw">return</span> fn_args<span class="op">.</span>into_iter()<span class="op">.</span>map(extract_arg_pat)<span class="op">.</span><span class="pp">collect::</span><span class="op">&lt;</span><span class="dt">Vec</span><span class="op">&lt;</span>_<span class="op">&gt;&gt;</span>()<span class="op">;</span></span>
230<span id="cb18-7"><a href="#cb18-7"></a><span class="op">}</span></span></code></pre></div> 230<span id="cb18-7"><a href="#cb18-7" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
231<p>Alright, so we are iterating over function args (<code>Punctuated</code> is a collection that you can iterate over) and mapping an <code>extract_arg_pat</code> to every item. What’s <code>extract_arg_pat</code>?</p> 231<p>Alright, so we are iterating over function args (<code>Punctuated</code> is a collection that you can iterate over) and mapping an <code>extract_arg_pat</code> to every item. What’s <code>extract_arg_pat</code>?</p>
232<div class="sourceCode" id="cb19"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb19-1"><a href="#cb19-1"></a><span class="co">// src/lib.rs</span></span> 232<div class="sourceCode" id="cb19"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true"></a><span class="co">// src/lib.rs</span></span>
233<span id="cb19-2"><a href="#cb19-2"></a></span> 233<span id="cb19-2"><a href="#cb19-2" aria-hidden="true"></a></span>
234<span id="cb19-3"><a href="#cb19-3"></a><span class="kw">fn</span> extract_arg_pat(a: FnArg) -&gt; <span class="dt">Box</span>&lt;Pat&gt; <span class="op">{</span></span> 234<span id="cb19-3"><a href="#cb19-3" aria-hidden="true"></a><span class="kw">fn</span> extract_arg_pat(a<span class="op">:</span> FnArg) <span class="op">-&gt;</span> <span class="dt">Box</span><span class="op">&lt;</span>Pat<span class="op">&gt;</span> <span class="op">{</span></span>
235<span id="cb19-4"><a href="#cb19-4"></a> <span class="kw">match</span> a <span class="op">{</span></span> 235<span id="cb19-4"><a href="#cb19-4" aria-hidden="true"></a> <span class="kw">match</span> a <span class="op">{</span></span>
236<span id="cb19-5"><a href="#cb19-5"></a> <span class="pp">FnArg::</span>Typed(p) =&gt; p.pat,</span> 236<span id="cb19-5"><a href="#cb19-5" aria-hidden="true"></a> <span class="pp">FnArg::</span>Typed(p) <span class="op">=&gt;</span> p<span class="op">.</span>pat<span class="op">,</span></span>
237<span id="cb19-6"><a href="#cb19-6"></a> _ =&gt; <span class="pp">panic!</span>(<span class="st">&quot;Not supported on types with `self`!&quot;</span>),</span> 237<span id="cb19-6"><a href="#cb19-6" aria-hidden="true"></a> _ <span class="op">=&gt;</span> <span class="pp">panic!</span>(<span class="st">&quot;Not supported on types with `self`!&quot;</span>)<span class="op">,</span></span>
238<span id="cb19-7"><a href="#cb19-7"></a> <span class="op">}</span></span> 238<span id="cb19-7"><a href="#cb19-7" aria-hidden="true"></a> <span class="op">}</span></span>
239<span id="cb19-8"><a href="#cb19-8"></a><span class="op">}</span></span></code></pre></div> 239<span id="cb19-8"><a href="#cb19-8" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
240<p><code>FnArg</code> is an enum type as you might have guessed. The <code>Typed</code> variant encompasses args that are written as <code>name: type</code> and the other variant, <code>Reciever</code> refers to <code>self</code> types. Ignore those for now, keep it simple.</p> 240<p><code>FnArg</code> is an enum type as you might have guessed. The <code>Typed</code> variant encompasses args that are written as <code>name: type</code> and the other variant, <code>Reciever</code> refers to <code>self</code> types. Ignore those for now, keep it simple.</p>
241<p>Every <code>FnArg::Typed</code> value contains a <code>pat</code>, which is in essence, the name of the argument. The type of the arg is accessible via <code>p.ty</code> (we will be using this later).</p> 241<p>Every <code>FnArg::Typed</code> value contains a <code>pat</code>, which is in essence, the name of the argument. The type of the arg is accessible via <code>p.ty</code> (we will be using this later).</p>
242<p>With that done, we should be able to write the codegen for the function body:</p> 242<p>With that done, we should be able to write the codegen for the function body:</p>
243<div class="sourceCode" id="cb20"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb20-1"><a href="#cb20-1"></a><span class="co">// src/lib.rs</span></span> 243<div class="sourceCode" id="cb20"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true"></a><span class="co">// src/lib.rs</span></span>
244<span id="cb20-2"><a href="#cb20-2"></a></span> 244<span id="cb20-2"><a href="#cb20-2" aria-hidden="true"></a></span>
245<span id="cb20-3"><a href="#cb20-3"></a><span class="kw">fn</span> generate_body(fn_args: &amp;<span class="op">[</span><span class="dt">Box</span>&lt;Pat&gt;<span class="op">]</span>, body: <span class="dt">Box</span>&lt;Block&gt;) -&gt; <span class="pp">proc_macro2::</span>TokenStream <span class="op">{</span></span> 245<span id="cb20-3"><a href="#cb20-3" aria-hidden="true"></a><span class="kw">fn</span> generate_body(fn_args<span class="op">:</span> <span class="op">&amp;</span>[<span class="dt">Box</span><span class="op">&lt;</span>Pat<span class="op">&gt;</span>]<span class="op">,</span> body<span class="op">:</span> <span class="dt">Box</span><span class="op">&lt;</span>Block<span class="op">&gt;</span>) <span class="op">-&gt;</span> <span class="pp">proc_macro2::</span>TokenStream <span class="op">{</span></span>
246<span id="cb20-4"><a href="#cb20-4"></a> <span class="pp">quote!</span> <span class="op">{</span></span> 246<span id="cb20-4"><a href="#cb20-4" aria-hidden="true"></a> <span class="pp">quote!</span> <span class="op">{</span></span>
247<span id="cb20-5"><a href="#cb20-5"></a> <span class="kw">return</span> #( <span class="kw">move</span> |#fn_args| )* #body</span> 247<span id="cb20-5"><a href="#cb20-5" aria-hidden="true"></a> <span class="kw">return</span> #( <span class="kw">move</span> <span class="op">|</span>#fn_args<span class="op">|</span> )<span class="op">*</span> #body</span>
248<span id="cb20-6"><a href="#cb20-6"></a> <span class="op">}</span></span> 248<span id="cb20-6"><a href="#cb20-6" aria-hidden="true"></a> <span class="op">}</span></span>
249<span id="cb20-7"><a href="#cb20-7"></a><span class="op">}</span></span></code></pre></div> 249<span id="cb20-7"><a href="#cb20-7" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
250<p>That is some scary looking syntax! Allow me to explain. The <code>quote!{ ... }</code> returns a <code>proc_macro2::TokenStream</code>, if we wrote <code>quote!{ let x = 1 + 2; }</code>, it wouldn’t create a new variable <code>x</code> with value 3, it would literally produce a stream of tokens with that expression.</p> 250<p>That is some scary looking syntax! Allow me to explain. The <code>quote!{ ... }</code> returns a <code>proc_macro2::TokenStream</code>, if we wrote <code>quote!{ let x = 1 + 2; }</code>, it wouldn’t create a new variable <code>x</code> with value 3, it would literally produce a stream of tokens with that expression.</p>
251<p>The <code>#</code> enables variable interpolation. <code>#body</code> will look for <code>body</code> in the current scope, take its value, and insert it in the returned <code>TokenStream</code>. Kinda like quasi quoting in LISPs, you have written one.</p> 251<p>The <code>#</code> enables variable interpolation. <code>#body</code> will look for <code>body</code> in the current scope, take its value, and insert it in the returned <code>TokenStream</code>. Kinda like quasi quoting in LISPs, you have written one.</p>
252<p>What about <code>#( move |#fn_args| )*</code>? That is repetition. <code>quote</code> iterates through <code>fn_args</code>, and drops a <code>move</code> behind each one, it then places pipes (<code>|</code>), around it.</p> 252<p>What about <code>#( move |#fn_args| )*</code>? That is repetition. <code>quote</code> iterates through <code>fn_args</code>, and drops a <code>move</code> behind each one, it then places pipes (<code>|</code>), around it.</p>
253<p>Let us test our first bit of codegen! Modify <code>generate_curry</code> like so:</p> 253<p>Let us test our first bit of codegen! Modify <code>generate_curry</code> like so:</p>
254<div class="sourceCode" id="cb21"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb21-1"><a href="#cb21-1"></a><span class="co">// src/lib.rs</span></span> 254<div class="sourceCode" id="cb21"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true"></a><span class="co">// src/lib.rs</span></span>
255<span id="cb21-2"><a href="#cb21-2"></a></span> 255<span id="cb21-2"><a href="#cb21-2" aria-hidden="true"></a></span>
256<span id="cb21-3"><a href="#cb21-3"></a> <span class="kw">fn</span> generate_curry(parsed: ItemFn) -&gt; TokenStream <span class="op">{</span></span> 256<span id="cb21-3"><a href="#cb21-3" aria-hidden="true"></a> <span class="kw">fn</span> generate_curry(parsed<span class="op">:</span> ItemFn) <span class="op">-&gt;</span> TokenStream <span class="op">{</span></span>
257<span id="cb21-4"><a href="#cb21-4"></a> <span class="kw">let</span> fn_body = parsed.block;</span> 257<span id="cb21-4"><a href="#cb21-4" aria-hidden="true"></a> <span class="kw">let</span> fn_body <span class="op">=</span> parsed<span class="op">.</span>block<span class="op">;</span></span>
258<span id="cb21-5"><a href="#cb21-5"></a> <span class="kw">let</span> sig = parsed.sig;</span> 258<span id="cb21-5"><a href="#cb21-5" aria-hidden="true"></a> <span class="kw">let</span> sig <span class="op">=</span> parsed<span class="op">.</span>sig<span class="op">;</span></span>
259<span id="cb21-6"><a href="#cb21-6"></a> <span class="kw">let</span> vis = parsed.vis;</span> 259<span id="cb21-6"><a href="#cb21-6" aria-hidden="true"></a> <span class="kw">let</span> vis <span class="op">=</span> parsed<span class="op">.</span>vis<span class="op">;</span></span>
260<span id="cb21-7"><a href="#cb21-7"></a> <span class="kw">let</span> fn_name = sig.ident;</span> 260<span id="cb21-7"><a href="#cb21-7" aria-hidden="true"></a> <span class="kw">let</span> fn_name <span class="op">=</span> sig<span class="op">.</span>ident<span class="op">;</span></span>
261<span id="cb21-8"><a href="#cb21-8"></a> <span class="kw">let</span> fn_args = sig.inputs;</span> 261<span id="cb21-8"><a href="#cb21-8" aria-hidden="true"></a> <span class="kw">let</span> fn_args <span class="op">=</span> sig<span class="op">.</span>inputs<span class="op">;</span></span>
262<span id="cb21-9"><a href="#cb21-9"></a> <span class="kw">let</span> fn_return_type = sig.output;</span> 262<span id="cb21-9"><a href="#cb21-9" aria-hidden="true"></a> <span class="kw">let</span> fn_return_type <span class="op">=</span> sig<span class="op">.</span>output<span class="op">;</span></span>
263<span id="cb21-10"><a href="#cb21-10"></a></span> 263<span id="cb21-10"><a href="#cb21-10" aria-hidden="true"></a></span>
264<span id="cb21-11"><a href="#cb21-11"></a>+ <span class="kw">let</span> arg_idents = extract_arg_idents(fn_args.clone());</span> 264<span id="cb21-11"><a href="#cb21-11" aria-hidden="true"></a><span class="op">+</span> <span class="kw">let</span> arg_idents <span class="op">=</span> extract_arg_idents(fn_args<span class="op">.</span>clone())<span class="op">;</span></span>
265<span id="cb21-12"><a href="#cb21-12"></a>+ <span class="kw">let</span> first_ident = &amp;arg_idents.first().unwrap();</span> 265<span id="cb21-12"><a href="#cb21-12" aria-hidden="true"></a><span class="op">+</span> <span class="kw">let</span> first_ident <span class="op">=</span> <span class="op">&amp;</span>arg_idents<span class="op">.</span>first()<span class="op">.</span>unwrap()<span class="op">;</span></span>
266<span id="cb21-13"><a href="#cb21-13"></a></span> 266<span id="cb21-13"><a href="#cb21-13" aria-hidden="true"></a></span>
267<span id="cb21-14"><a href="#cb21-14"></a>+ <span class="co">// remember, our curried body starts with the second argument!</span></span> 267<span id="cb21-14"><a href="#cb21-14" aria-hidden="true"></a><span class="op">+</span> <span class="co">// remember, our curried body starts with the second argument!</span></span>
268<span id="cb21-15"><a href="#cb21-15"></a>+ <span class="kw">let</span> curried_body = generate_body(&amp;arg_idents<span class="op">[</span><span class="dv">1</span>..<span class="op">]</span>, fn_body.clone());</span> 268<span id="cb21-15"><a href="#cb21-15" aria-hidden="true"></a><span class="op">+</span> <span class="kw">let</span> curried_body <span class="op">=</span> generate_body(<span class="op">&amp;</span>arg_idents[<span class="dv">1</span><span class="op">..</span>]<span class="op">,</span> fn_body<span class="op">.</span>clone())<span class="op">;</span></span>
269<span id="cb21-16"><a href="#cb21-16"></a>+ <span class="pp">println!</span>(<span class="st">&quot;{}&quot;</span>, curried_body);</span> 269<span id="cb21-16"><a href="#cb21-16" aria-hidden="true"></a><span class="op">+</span> <span class="pp">println!</span>(<span class="st">&quot;{}&quot;</span><span class="op">,</span> curried_body)<span class="op">;</span></span>
270<span id="cb21-17"><a href="#cb21-17"></a></span> 270<span id="cb21-17"><a href="#cb21-17" aria-hidden="true"></a></span>
271<span id="cb21-18"><a href="#cb21-18"></a> <span class="kw">return</span> <span class="pp">TokenStream::</span>new();</span> 271<span id="cb21-18"><a href="#cb21-18" aria-hidden="true"></a> <span class="kw">return</span> <span class="pp">TokenStream::</span>new()<span class="op">;</span></span>
272<span id="cb21-19"><a href="#cb21-19"></a> <span class="op">}</span></span></code></pre></div> 272<span id="cb21-19"><a href="#cb21-19" aria-hidden="true"></a> <span class="op">}</span></span></code></pre></div>
273<p>Add a little test to <code>tests/</code>:</p> 273<p>Add a little test to <code>tests/</code>:</p>
274<div class="sourceCode" id="cb22"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb22-1"><a href="#cb22-1"></a><span class="co">// tests/smoke.rs</span></span> 274<div class="sourceCode" id="cb22"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true"></a><span class="co">// tests/smoke.rs</span></span>
275<span id="cb22-2"><a href="#cb22-2"></a></span> 275<span id="cb22-2"><a href="#cb22-2" aria-hidden="true"></a></span>
276<span id="cb22-3"><a href="#cb22-3"></a><span class="at">#[</span><span class="pp">currying::</span>curry<span class="at">]</span></span> 276<span id="cb22-3"><a href="#cb22-3" aria-hidden="true"></a><span class="at">#[</span><span class="pp">currying::</span>curry<span class="at">]</span></span>
277<span id="cb22-4"><a href="#cb22-4"></a><span class="kw">fn</span> add(x: <span class="dt">u32</span>, y: <span class="dt">u32</span>, z: <span class="dt">u32</span>) -&gt; <span class="dt">u32</span> <span class="op">{</span></span> 277<span id="cb22-4"><a href="#cb22-4" aria-hidden="true"></a><span class="kw">fn</span> add(x<span class="op">:</span> <span class="dt">u32</span><span class="op">,</span> y<span class="op">:</span> <span class="dt">u32</span><span class="op">,</span> z<span class="op">:</span> <span class="dt">u32</span>) <span class="op">-&gt;</span> <span class="dt">u32</span> <span class="op">{</span></span>
278<span id="cb22-5"><a href="#cb22-5"></a> x + y + z</span> 278<span id="cb22-5"><a href="#cb22-5" aria-hidden="true"></a> x <span class="op">+</span> y <span class="op">+</span> z</span>
279<span id="cb22-6"><a href="#cb22-6"></a><span class="op">}</span></span> 279<span id="cb22-6"><a href="#cb22-6" aria-hidden="true"></a><span class="op">}</span></span>
280<span id="cb22-7"><a href="#cb22-7"></a></span> 280<span id="cb22-7"><a href="#cb22-7" aria-hidden="true"></a></span>
281<span id="cb22-8"><a href="#cb22-8"></a><span class="at">#[</span>test<span class="at">]</span></span> 281<span id="cb22-8"><a href="#cb22-8" aria-hidden="true"></a><span class="at">#[</span>test<span class="at">]</span></span>
282<span id="cb22-9"><a href="#cb22-9"></a><span class="kw">fn</span> works() <span class="op">{</span></span> 282<span id="cb22-9"><a href="#cb22-9" aria-hidden="true"></a><span class="kw">fn</span> works() <span class="op">{</span></span>
283<span id="cb22-10"><a href="#cb22-10"></a> <span class="pp">assert!</span>(<span class="cn">true</span>);</span> 283<span id="cb22-10"><a href="#cb22-10" aria-hidden="true"></a> <span class="pp">assert!</span>(<span class="cn">true</span>)<span class="op">;</span></span>
284<span id="cb22-11"><a href="#cb22-11"></a><span class="op">}</span></span></code></pre></div> 284<span id="cb22-11"><a href="#cb22-11" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
285<p>You should find something like this in the output of <code>cargo test</code>:</p> 285<p>You should find something like this in the output of <code>cargo test</code>:</p>
286<pre><code>return move | y | move | z | { x + y + z }</code></pre> 286<pre><code>return move | y | move | z | { x + y + z }</code></pre>
287<p>Glorious <code>println!</code> debugging!</p> 287<p>Glorious <code>println!</code> debugging!</p>
288<h4 id="function-signature">Function signature</h4> 288<h4 id="function-signature">Function signature</h4>
289<p>This section gets into the more complicated bits of the macro, generating type aliases and the function signature. By the end of this section, we should have a full working auto-currying macro!</p> 289<p>This section gets into the more complicated bits of the macro, generating type aliases and the function signature. By the end of this section, we should have a full working auto-currying macro!</p>
290<p>Recall what our generated type aliases should look like, for our <code>add</code> function:</p> 290<p>Recall what our generated type aliases should look like, for our <code>add</code> function:</p>
291<div class="sourceCode" id="cb24"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb24-1"><a href="#cb24-1"></a><span class="kw">type</span> T0 = <span class="dt">u32</span>;</span> 291<div class="sourceCode" id="cb24"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true"></a><span class="kw">type</span> T0 <span class="op">=</span> <span class="dt">u32</span><span class="op">;</span></span>
292<span id="cb24-2"><a href="#cb24-2"></a><span class="kw">type</span> T1 = <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; T0;</span> 292<span id="cb24-2"><a href="#cb24-2" aria-hidden="true"></a><span class="kw">type</span> T1 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> T0<span class="op">;</span></span>
293<span id="cb24-3"><a href="#cb24-3"></a><span class="kw">type</span> T2 = <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; T1;</span></code></pre></div> 293<span id="cb24-3"><a href="#cb24-3" aria-hidden="true"></a><span class="kw">type</span> T2 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> T1<span class="op">;</span></span></code></pre></div>
294<p>In general:</p> 294<p>In general:</p>
295<div class="sourceCode" id="cb25"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb25-1"><a href="#cb25-1"></a><span class="kw">type</span> T0 = &lt;<span class="kw">return</span> <span class="kw">type</span>&gt;;</span> 295<div class="sourceCode" id="cb25"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true"></a><span class="kw">type</span> T0 <span class="op">=</span> <span class="op">&lt;</span><span class="kw">return</span> <span class="kw">type</span>&gt;<span class="op">;</span></span>
296<span id="cb25-2"><a href="#cb25-2"></a><span class="kw">type</span> T1 = <span class="kw">impl</span> <span class="bu">Fn</span>(&lt;<span class="kw">type</span> of arg N&gt;) -&gt; T0;</span> 296<span id="cb25-2"><a href="#cb25-2" aria-hidden="true"></a><span class="kw">type</span> T1 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="op">&lt;</span><span class="kw">type</span> of arg N&gt;) -&gt; T0<span class="op">;</span></span>
297<span id="cb25-3"><a href="#cb25-3"></a><span class="kw">type</span> T2 = <span class="kw">impl</span> <span class="bu">Fn</span>(&lt;<span class="kw">type</span> of arg N - 1&gt;) -&gt; T1;</span> 297<span id="cb25-3"><a href="#cb25-3" aria-hidden="true"></a><span class="kw">type</span> T2 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="op">&lt;</span><span class="kw">type</span> of arg N - 1&gt;) -&gt; T1<span class="op">;</span></span>
298<span id="cb25-4"><a href="#cb25-4"></a>.</span> 298<span id="cb25-4"><a href="#cb25-4" aria-hidden="true"></a><span class="op">.</span></span>
299<span id="cb25-5"><a href="#cb25-5"></a>.</span> 299<span id="cb25-5"><a href="#cb25-5" aria-hidden="true"></a><span class="op">.</span></span>
300<span id="cb25-6"><a href="#cb25-6"></a>.</span> 300<span id="cb25-6"><a href="#cb25-6" aria-hidden="true"></a><span class="op">.</span></span>
301<span id="cb25-7"><a href="#cb25-7"></a><span class="kw">type</span> T(N-1) = <span class="kw">impl</span> <span class="bu">Fn</span>(&lt;<span class="kw">type</span> of arg 2&gt;) -&gt; T(N-2);</span></code></pre></div> 301<span id="cb25-7"><a href="#cb25-7" aria-hidden="true"></a><span class="kw">type</span> T(N-1) <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="op">&lt;</span><span class="kw">type</span> of arg 2&gt;) -&gt; T(N-2)<span class="op">;</span></span></code></pre></div>
302<p>To codegen that, we need the types of:</p> 302<p>To codegen that, we need the types of:</p>
303<ul> 303<ul>
304<li>all our inputs (arguments)</li> 304<li>all our inputs (arguments)</li>
305<li>the output (the return type)</li> 305<li>the output (the return type)</li>
306</ul> 306</ul>
307<p>To fetch the types of all our inputs, we can simply reuse the bits we wrote to fetch the names of all our inputs! (doc: <a href="https://docs.rs/syn/1.0.18/syn/enum.Type.html">Type</a>)</p> 307<p>To fetch the types of all our inputs, we can simply reuse the bits we wrote to fetch the names of all our inputs! (doc: <a href="https://docs.rs/syn/1.0.18/syn/enum.Type.html">Type</a>)</p>
308<div class="sourceCode" id="cb26"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb26-1"><a href="#cb26-1"></a><span class="co">// src/lib.rs</span></span> 308<div class="sourceCode" id="cb26"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true"></a><span class="co">// src/lib.rs</span></span>
309<span id="cb26-2"><a href="#cb26-2"></a></span> 309<span id="cb26-2"><a href="#cb26-2" aria-hidden="true"></a></span>
310<span id="cb26-3"><a href="#cb26-3"></a><span class="kw">use</span> <span class="pp">syn::</span><span class="op">{</span>parse_macro_input, Block, FnArg, ItemFn, Pat, ReturnType, Type<span class="op">}</span>;</span> 310<span id="cb26-3"><a href="#cb26-3" aria-hidden="true"></a><span class="kw">use</span> <span class="pp">syn::</span><span class="op">{</span>parse_macro_input<span class="op">,</span> Block<span class="op">,</span> FnArg<span class="op">,</span> ItemFn<span class="op">,</span> Pat<span class="op">,</span> ReturnType<span class="op">,</span> Type<span class="op">};</span></span>
311<span id="cb26-4"><a href="#cb26-4"></a></span> 311<span id="cb26-4"><a href="#cb26-4" aria-hidden="true"></a></span>
312<span id="cb26-5"><a href="#cb26-5"></a><span class="kw">fn</span> extract_type(a: FnArg) -&gt; <span class="dt">Box</span>&lt;Type&gt; <span class="op">{</span></span> 312<span id="cb26-5"><a href="#cb26-5" aria-hidden="true"></a><span class="kw">fn</span> extract_type(a<span class="op">:</span> FnArg) <span class="op">-&gt;</span> <span class="dt">Box</span><span class="op">&lt;</span>Type<span class="op">&gt;</span> <span class="op">{</span></span>
313<span id="cb26-6"><a href="#cb26-6"></a> <span class="kw">match</span> a <span class="op">{</span></span> 313<span id="cb26-6"><a href="#cb26-6" aria-hidden="true"></a> <span class="kw">match</span> a <span class="op">{</span></span>
314<span id="cb26-7"><a href="#cb26-7"></a> <span class="pp">FnArg::</span>Typed(p) =&gt; p.ty, <span class="co">// notice `ty` instead of `pat`</span></span> 314<span id="cb26-7"><a href="#cb26-7" aria-hidden="true"></a> <span class="pp">FnArg::</span>Typed(p) <span class="op">=&gt;</span> p<span class="op">.</span>ty<span class="op">,</span> <span class="co">// notice `ty` instead of `pat`</span></span>
315<span id="cb26-8"><a href="#cb26-8"></a> _ =&gt; <span class="pp">panic!</span>(<span class="st">&quot;Not supported on types with `self`!&quot;</span>),</span> 315<span id="cb26-8"><a href="#cb26-8" aria-hidden="true"></a> _ <span class="op">=&gt;</span> <span class="pp">panic!</span>(<span class="st">&quot;Not supported on types with `self`!&quot;</span>)<span class="op">,</span></span>
316<span id="cb26-9"><a href="#cb26-9"></a> <span class="op">}</span></span> 316<span id="cb26-9"><a href="#cb26-9" aria-hidden="true"></a> <span class="op">}</span></span>
317<span id="cb26-10"><a href="#cb26-10"></a><span class="op">}</span></span> 317<span id="cb26-10"><a href="#cb26-10" aria-hidden="true"></a><span class="op">}</span></span>
318<span id="cb26-11"><a href="#cb26-11"></a></span> 318<span id="cb26-11"><a href="#cb26-11" aria-hidden="true"></a></span>
319<span id="cb26-12"><a href="#cb26-12"></a><span class="kw">fn</span> extract_arg_types(fn_args: Punctuated&lt;FnArg, <span class="pp">syn::token::</span>Comma&gt;) -&gt; <span class="dt">Vec</span>&lt;<span class="dt">Box</span>&lt;Type&gt;&gt; <span class="op">{</span></span> 319<span id="cb26-12"><a href="#cb26-12" aria-hidden="true"></a><span class="kw">fn</span> extract_arg_types(fn_args<span class="op">:</span> Punctuated<span class="op">&lt;</span>FnArg<span class="op">,</span> <span class="pp">syn::token::</span>Comma<span class="op">&gt;</span>) <span class="op">-&gt;</span> <span class="dt">Vec</span><span class="op">&lt;</span><span class="dt">Box</span><span class="op">&lt;</span>Type<span class="op">&gt;&gt;</span> <span class="op">{</span></span>
320<span id="cb26-13"><a href="#cb26-13"></a> <span class="kw">return</span> fn_args.into_iter().map(extract_type).<span class="pp">collect::</span>&lt;<span class="dt">Vec</span>&lt;_&gt;&gt;();</span> 320<span id="cb26-13"><a href="#cb26-13" aria-hidden="true"></a> <span class="kw">return</span> fn_args<span class="op">.</span>into_iter()<span class="op">.</span>map(extract_type)<span class="op">.</span><span class="pp">collect::</span><span class="op">&lt;</span><span class="dt">Vec</span><span class="op">&lt;</span>_<span class="op">&gt;&gt;</span>()<span class="op">;</span></span>
321<span id="cb26-14"><a href="#cb26-14"></a></span> 321<span id="cb26-14"><a href="#cb26-14" aria-hidden="true"></a></span>
322<span id="cb26-15"><a href="#cb26-15"></a><span class="op">}</span></span></code></pre></div> 322<span id="cb26-15"><a href="#cb26-15" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
323<p>A good reader would have looked at the docs for output member of the <code>syn::Signature</code> struct. It has the type <code>syn::ReturnType</code>. So there is no extraction to do here right? There are actually a couple of things we have to ensure here:</p> 323<p>A good reader would have looked at the docs for output member of the <code>syn::Signature</code> struct. It has the type <code>syn::ReturnType</code>. So there is no extraction to do here right? There are actually a couple of things we have to ensure here:</p>
324<ol type="1"> 324<ol type="1">
325<li><p>We need to ensure that the function returns! A function that does not return is pointless in this case, and I will tell you why, in the <a href="#notes">Notes</a> section.</p></li> 325<li><p>We need to ensure that the function returns! A function that does not return is pointless in this case, and I will tell you why, in the <a href="#notes">Notes</a> section.</p></li>
326<li><p>A <code>ReturnType</code> encloses the arrow of the return as well, we need to get rid of that. Recall:</p> 326<li><p>A <code>ReturnType</code> encloses the arrow of the return as well, we need to get rid of that. Recall:</p>
327<div class="sourceCode" id="cb27"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb27-1"><a href="#cb27-1"></a><span class="kw">type</span> T0 = <span class="dt">u32</span></span> 327<div class="sourceCode" id="cb27"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true"></a><span class="kw">type</span> T0 <span class="op">=</span> <span class="dt">u32</span></span>
328<span id="cb27-2"><a href="#cb27-2"></a><span class="co">// and not</span></span> 328<span id="cb27-2"><a href="#cb27-2" aria-hidden="true"></a><span class="co">// and not</span></span>
329<span id="cb27-3"><a href="#cb27-3"></a><span class="kw">type</span> T0 = -&gt; <span class="dt">u32</span></span></code></pre></div></li> 329<span id="cb27-3"><a href="#cb27-3" aria-hidden="true"></a><span class="kw">type</span> T0 <span class="op">=</span> <span class="op">-&gt;</span> <span class="dt">u32</span></span></code></pre></div></li>
330</ol> 330</ol>
331<p>Here is the snippet that handles extraction of the return type (doc: <a href="https://docs.rs/syn/1.0.19/syn/enum.ReturnType.html">syn::ReturnType</a>):</p> 331<p>Here is the snippet that handles extraction of the return type (doc: <a href="https://docs.rs/syn/1.0.19/syn/enum.ReturnType.html">syn::ReturnType</a>):</p>
332<div class="sourceCode" id="cb28"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb28-1"><a href="#cb28-1"></a><span class="co">// src/lib.rs</span></span> 332<div class="sourceCode" id="cb28"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true"></a><span class="co">// src/lib.rs</span></span>
333<span id="cb28-2"><a href="#cb28-2"></a></span> 333<span id="cb28-2"><a href="#cb28-2" aria-hidden="true"></a></span>
334<span id="cb28-3"><a href="#cb28-3"></a><span class="kw">fn</span> extract_return_type(a: ReturnType) -&gt; <span class="dt">Box</span>&lt;Type&gt; <span class="op">{</span></span> 334<span id="cb28-3"><a href="#cb28-3" aria-hidden="true"></a><span class="kw">fn</span> extract_return_type(a<span class="op">:</span> ReturnType) <span class="op">-&gt;</span> <span class="dt">Box</span><span class="op">&lt;</span>Type<span class="op">&gt;</span> <span class="op">{</span></span>
335<span id="cb28-4"><a href="#cb28-4"></a> <span class="kw">match</span> a <span class="op">{</span></span> 335<span id="cb28-4"><a href="#cb28-4" aria-hidden="true"></a> <span class="kw">match</span> a <span class="op">{</span></span>
336<span id="cb28-5"><a href="#cb28-5"></a> <span class="pp">ReturnType::</span>Type(_, p) =&gt; p,</span> 336<span id="cb28-5"><a href="#cb28-5" aria-hidden="true"></a> <span class="pp">ReturnType::</span>Type(_<span class="op">,</span> p) <span class="op">=&gt;</span> p<span class="op">,</span></span>
337<span id="cb28-6"><a href="#cb28-6"></a> _ =&gt; <span class="pp">panic!</span>(<span class="st">&quot;Not supported on functions without return types!&quot;</span>),</span> 337<span id="cb28-6"><a href="#cb28-6" aria-hidden="true"></a> _ <span class="op">=&gt;</span> <span class="pp">panic!</span>(<span class="st">&quot;Not supported on functions without return types!&quot;</span>)<span class="op">,</span></span>
338<span id="cb28-7"><a href="#cb28-7"></a> <span class="op">}</span></span> 338<span id="cb28-7"><a href="#cb28-7" aria-hidden="true"></a> <span class="op">}</span></span>
339<span id="cb28-8"><a href="#cb28-8"></a><span class="op">}</span></span></code></pre></div> 339<span id="cb28-8"><a href="#cb28-8" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
340<p>You might notice that we are making extensive use of the <code>panic!</code> macro. Well, that is because it is a good idea to quit on receiving an unsatisfactory <code>TokenStream</code>.</p> 340<p>You might notice that we are making extensive use of the <code>panic!</code> macro. Well, that is because it is a good idea to quit on receiving an unsatisfactory <code>TokenStream</code>.</p>
341<p>With all our types ready, we can get on with generating type aliases:</p> 341<p>With all our types ready, we can get on with generating type aliases:</p>
342<div class="sourceCode" id="cb29"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb29-1"><a href="#cb29-1"></a><span class="co">// src/lib.rs</span></span> 342<div class="sourceCode" id="cb29"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true"></a><span class="co">// src/lib.rs</span></span>
343<span id="cb29-2"><a href="#cb29-2"></a></span> 343<span id="cb29-2"><a href="#cb29-2" aria-hidden="true"></a></span>
344<span id="cb29-3"><a href="#cb29-3"></a><span class="kw">use</span> <span class="pp">quote::</span><span class="op">{</span>quote, format_ident<span class="op">}</span>;</span> 344<span id="cb29-3"><a href="#cb29-3" aria-hidden="true"></a><span class="kw">use</span> <span class="pp">quote::</span><span class="op">{</span>quote<span class="op">,</span> format_ident<span class="op">};</span></span>
345<span id="cb29-4"><a href="#cb29-4"></a></span> 345<span id="cb29-4"><a href="#cb29-4" aria-hidden="true"></a></span>
346<span id="cb29-5"><a href="#cb29-5"></a><span class="kw">fn</span> generate_type_aliases(</span> 346<span id="cb29-5"><a href="#cb29-5" aria-hidden="true"></a><span class="kw">fn</span> generate_type_aliases(</span>
347<span id="cb29-6"><a href="#cb29-6"></a> fn_arg_types: &amp;<span class="op">[</span><span class="dt">Box</span>&lt;Type&gt;<span class="op">]</span>,</span> 347<span id="cb29-6"><a href="#cb29-6" aria-hidden="true"></a> fn_arg_types<span class="op">:</span> <span class="op">&amp;</span>[<span class="dt">Box</span><span class="op">&lt;</span>Type<span class="op">&gt;</span>]<span class="op">,</span></span>
348<span id="cb29-7"><a href="#cb29-7"></a> fn_return_type: <span class="dt">Box</span>&lt;Type&gt;,</span> 348<span id="cb29-7"><a href="#cb29-7" aria-hidden="true"></a> fn_return_type<span class="op">:</span> <span class="dt">Box</span><span class="op">&lt;</span>Type<span class="op">&gt;,</span></span>
349<span id="cb29-8"><a href="#cb29-8"></a> fn_name: &amp;<span class="pp">syn::</span>Ident,</span> 349<span id="cb29-8"><a href="#cb29-8" aria-hidden="true"></a> fn_name<span class="op">:</span> <span class="op">&amp;</span><span class="pp">syn::</span>Ident<span class="op">,</span></span>
350<span id="cb29-9"><a href="#cb29-9"></a>) -&gt; <span class="dt">Vec</span>&lt;<span class="pp">proc_macro2::</span>TokenStream&gt; <span class="op">{</span> <span class="co">// 1</span></span> 350<span id="cb29-9"><a href="#cb29-9" aria-hidden="true"></a>) <span class="op">-&gt;</span> <span class="dt">Vec</span><span class="op">&lt;</span><span class="pp">proc_macro2::</span>TokenStream<span class="op">&gt;</span> <span class="op">{</span> <span class="co">// 1</span></span>
351<span id="cb29-10"><a href="#cb29-10"></a></span> 351<span id="cb29-10"><a href="#cb29-10" aria-hidden="true"></a></span>
352<span id="cb29-11"><a href="#cb29-11"></a> <span class="kw">let</span> type_t0 = <span class="pp">format_ident!</span>(<span class="st">&quot;_{}_T0&quot;</span>, fn_name); <span class="co">// 2</span></span> 352<span id="cb29-11"><a href="#cb29-11" aria-hidden="true"></a> <span class="kw">let</span> type_t0 <span class="op">=</span> <span class="pp">format_ident!</span>(<span class="st">&quot;_{}_T0&quot;</span><span class="op">,</span> fn_name)<span class="op">;</span> <span class="co">// 2</span></span>
353<span id="cb29-12"><a href="#cb29-12"></a> <span class="kw">let</span> <span class="kw">mut</span> type_aliases = <span class="pp">vec!</span><span class="op">[</span><span class="pp">quote!</span> <span class="op">{</span> <span class="kw">type</span> #type_t0 = #fn_return_type <span class="op">}]</span>;</span> 353<span id="cb29-12"><a href="#cb29-12" aria-hidden="true"></a> <span class="kw">let</span> <span class="kw">mut</span> type_aliases <span class="op">=</span> <span class="pp">vec!</span>[<span class="pp">quote!</span> <span class="op">{</span> <span class="kw">type</span> #type_t0 <span class="op">=</span> #fn_return_type <span class="op">}</span>]<span class="op">;</span></span>
354<span id="cb29-13"><a href="#cb29-13"></a></span> 354<span id="cb29-13"><a href="#cb29-13" aria-hidden="true"></a></span>
355<span id="cb29-14"><a href="#cb29-14"></a> <span class="co">// 3</span></span> 355<span id="cb29-14"><a href="#cb29-14" aria-hidden="true"></a> <span class="co">// 3</span></span>
356<span id="cb29-15"><a href="#cb29-15"></a> <span class="kw">for</span> (i, t) <span class="kw">in</span> (<span class="dv">1</span>..).zip(fn_arg_types.into_iter().rev()) <span class="op">{</span></span> 356<span id="cb29-15"><a href="#cb29-15" aria-hidden="true"></a> <span class="kw">for</span> (i<span class="op">,</span> t) <span class="kw">in</span> (<span class="dv">1</span><span class="op">..</span>)<span class="op">.</span>zip(fn_arg_types<span class="op">.</span>into_iter()<span class="op">.</span>rev()) <span class="op">{</span></span>
357<span id="cb29-16"><a href="#cb29-16"></a> <span class="kw">let</span> p = <span class="pp">format_ident!</span>(<span class="st">&quot;_{}_{}&quot;</span>, fn_name, <span class="pp">format!</span>(<span class="st">&quot;T{}&quot;</span>, i - <span class="dv">1</span>));</span> 357<span id="cb29-16"><a href="#cb29-16" aria-hidden="true"></a> <span class="kw">let</span> p <span class="op">=</span> <span class="pp">format_ident!</span>(<span class="st">&quot;_{}_{}&quot;</span><span class="op">,</span> fn_name<span class="op">,</span> <span class="pp">format!</span>(<span class="st">&quot;T{}&quot;</span><span class="op">,</span> i <span class="op">-</span> <span class="dv">1</span>))<span class="op">;</span></span>
358<span id="cb29-17"><a href="#cb29-17"></a> <span class="kw">let</span> n = <span class="pp">format_ident!</span>(<span class="st">&quot;_{}_{}&quot;</span>, fn_name, <span class="pp">format!</span>(<span class="st">&quot;T{}&quot;</span>, i));</span> 358<span id="cb29-17"><a href="#cb29-17" aria-hidden="true"></a> <span class="kw">let</span> n <span class="op">=</span> <span class="pp">format_ident!</span>(<span class="st">&quot;_{}_{}&quot;</span><span class="op">,</span> fn_name<span class="op">,</span> <span class="pp">format!</span>(<span class="st">&quot;T{}&quot;</span><span class="op">,</span> i))<span class="op">;</span></span>
359<span id="cb29-18"><a href="#cb29-18"></a></span> 359<span id="cb29-18"><a href="#cb29-18" aria-hidden="true"></a></span>
360<span id="cb29-19"><a href="#cb29-19"></a> type_aliases.push(<span class="pp">quote!</span> <span class="op">{</span></span> 360<span id="cb29-19"><a href="#cb29-19" aria-hidden="true"></a> type_aliases<span class="op">.</span>push(<span class="pp">quote!</span> <span class="op">{</span></span>
361<span id="cb29-20"><a href="#cb29-20"></a> <span class="kw">type</span> #n = <span class="kw">impl</span> <span class="bu">Fn</span>(#t) -&gt; #p</span> 361<span id="cb29-20"><a href="#cb29-20" aria-hidden="true"></a> <span class="kw">type</span> #n <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(#t) <span class="op">-&gt;</span> #p</span>
362<span id="cb29-21"><a href="#cb29-21"></a> <span class="op">}</span>);</span> 362<span id="cb29-21"><a href="#cb29-21" aria-hidden="true"></a> <span class="op">}</span>)<span class="op">;</span></span>
363<span id="cb29-22"><a href="#cb29-22"></a> <span class="op">}</span></span> 363<span id="cb29-22"><a href="#cb29-22" aria-hidden="true"></a> <span class="op">}</span></span>
364<span id="cb29-23"><a href="#cb29-23"></a></span> 364<span id="cb29-23"><a href="#cb29-23" aria-hidden="true"></a></span>
365<span id="cb29-24"><a href="#cb29-24"></a> <span class="kw">return</span> type_aliases;</span> 365<span id="cb29-24"><a href="#cb29-24" aria-hidden="true"></a> <span class="kw">return</span> type_aliases<span class="op">;</span></span>
366<span id="cb29-25"><a href="#cb29-25"></a><span class="op">}</span></span></code></pre></div> 366<span id="cb29-25"><a href="#cb29-25" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
367<p><strong>1. The return value</strong><br /> 367<p><strong>1. The return value</strong><br />
368We are returning a <code>Vec&lt;proc_macro2::TokenStream&gt;</code>, i. e., a list of <code>TokenStream</code>s, where each item is a type alias.</p> 368We are returning a <code>Vec&lt;proc_macro2::TokenStream&gt;</code>, i. e., a list of <code>TokenStream</code>s, where each item is a type alias.</p>
369<p><strong>2. Format identifier?</strong><br /> 369<p><strong>2. Format identifier?</strong><br />
370I’ve got some explanation to do on this line. Clearly, we are trying to write the first type alias, and initialize our <code>TokenStream</code> vector with <code>T0</code>, because it is different from the others:</p> 370I’ve got some explanation to do on this line. Clearly, we are trying to write the first type alias, and initialize our <code>TokenStream</code> vector with <code>T0</code>, because it is different from the others:</p>
371<div class="sourceCode" id="cb30"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb30-1"><a href="#cb30-1"></a><span class="kw">type</span> T0 = something</span> 371<div class="sourceCode" id="cb30"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true"></a><span class="kw">type</span> T0 <span class="op">=</span> something</span>
372<span id="cb30-2"><a href="#cb30-2"></a><span class="co">// the others are of the form</span></span> 372<span id="cb30-2"><a href="#cb30-2" aria-hidden="true"></a><span class="co">// the others are of the form</span></span>
373<span id="cb30-3"><a href="#cb30-3"></a><span class="kw">type</span> Tr = <span class="kw">impl</span> <span class="bu">Fn</span>(something) -&gt; something</span></code></pre></div> 373<span id="cb30-3"><a href="#cb30-3" aria-hidden="true"></a><span class="kw">type</span> Tr <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(something) <span class="op">-&gt;</span> something</span></code></pre></div>
374<p><code>format_ident!</code> is similar to <code>format!</code>. Instead of returning a formatted string, it returns a <code>syn::Ident</code>. Therefore, <code>type_t0</code> is actually an identifier for, in the case of our <code>add</code> function, <code>_add_T0</code>. Why is this formatting important? Namespacing.</p> 374<p><code>format_ident!</code> is similar to <code>format!</code>. Instead of returning a formatted string, it returns a <code>syn::Ident</code>. Therefore, <code>type_t0</code> is actually an identifier for, in the case of our <code>add</code> function, <code>_add_T0</code>. Why is this formatting important? Namespacing.</p>
375<p>Picture this, we have two functions, <code>add</code> and <code>subtract</code>, that we wish to curry with our macro:</p> 375<p>Picture this, we have two functions, <code>add</code> and <code>subtract</code>, that we wish to curry with our macro:</p>
376<div class="sourceCode" id="cb31"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb31-1"><a href="#cb31-1"></a><span class="at">#[</span>curry<span class="at">]</span></span> 376<div class="sourceCode" id="cb31"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true"></a><span class="at">#[</span>curry<span class="at">]</span></span>
377<span id="cb31-2"><a href="#cb31-2"></a><span class="kw">fn</span> add(...) -&gt; <span class="dt">u32</span> <span class="op">{</span> ... <span class="op">}</span></span> 377<span id="cb31-2"><a href="#cb31-2" aria-hidden="true"></a><span class="kw">fn</span> add(<span class="op">...</span>) <span class="op">-&gt;</span> <span class="dt">u32</span> <span class="op">{</span> <span class="op">...</span> <span class="op">}</span></span>
378<span id="cb31-3"><a href="#cb31-3"></a></span> 378<span id="cb31-3"><a href="#cb31-3" aria-hidden="true"></a></span>
379<span id="cb31-4"><a href="#cb31-4"></a><span class="at">#[</span>curry<span class="at">]</span></span> 379<span id="cb31-4"><a href="#cb31-4" aria-hidden="true"></a><span class="at">#[</span>curry<span class="at">]</span></span>
380<span id="cb31-5"><a href="#cb31-5"></a><span class="kw">fn</span> sub(...) -&gt; <span class="dt">u32</span> <span class="op">{</span> ... <span class="op">}</span></span></code></pre></div> 380<span id="cb31-5"><a href="#cb31-5" aria-hidden="true"></a><span class="kw">fn</span> sub(<span class="op">...</span>) <span class="op">-&gt;</span> <span class="dt">u32</span> <span class="op">{</span> <span class="op">...</span> <span class="op">}</span></span></code></pre></div>
381<p>Here is the same but with macros expanded:</p> 381<p>Here is the same but with macros expanded:</p>
382<div class="sourceCode" id="cb32"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb32-1"><a href="#cb32-1"></a><span class="kw">type</span> T0 = <span class="dt">u32</span>;</span> 382<div class="sourceCode" id="cb32"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true"></a><span class="kw">type</span> T0 <span class="op">=</span> <span class="dt">u32</span><span class="op">;</span></span>
383<span id="cb32-2"><a href="#cb32-2"></a><span class="kw">type</span> T1 = <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; T0;</span> 383<span id="cb32-2"><a href="#cb32-2" aria-hidden="true"></a><span class="kw">type</span> T1 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> T0<span class="op">;</span></span>
384<span id="cb32-3"><a href="#cb32-3"></a><span class="kw">fn</span> add( ... ) -&gt; T1 <span class="op">{</span> ... <span class="op">}</span></span> 384<span id="cb32-3"><a href="#cb32-3" aria-hidden="true"></a><span class="kw">fn</span> add( <span class="op">...</span> ) <span class="op">-&gt;</span> T1 <span class="op">{</span> <span class="op">...</span> <span class="op">}</span></span>
385<span id="cb32-4"><a href="#cb32-4"></a></span> 385<span id="cb32-4"><a href="#cb32-4" aria-hidden="true"></a></span>
386<span id="cb32-5"><a href="#cb32-5"></a><span class="kw">type</span> T0 = <span class="dt">u32</span>;</span> 386<span id="cb32-5"><a href="#cb32-5" aria-hidden="true"></a><span class="kw">type</span> T0 <span class="op">=</span> <span class="dt">u32</span><span class="op">;</span></span>
387<span id="cb32-6"><a href="#cb32-6"></a><span class="kw">type</span> T1 = <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; T0;</span> 387<span id="cb32-6"><a href="#cb32-6" aria-hidden="true"></a><span class="kw">type</span> T1 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> T0<span class="op">;</span></span>
388<span id="cb32-7"><a href="#cb32-7"></a><span class="kw">fn</span> sub( ... ) -&gt; T1 <span class="op">{</span> ... <span class="op">}</span></span></code></pre></div> 388<span id="cb32-7"><a href="#cb32-7" aria-hidden="true"></a><span class="kw">fn</span> sub( <span class="op">...</span> ) <span class="op">-&gt;</span> T1 <span class="op">{</span> <span class="op">...</span> <span class="op">}</span></span></code></pre></div>
389<p>We end up with two definitions of <code>T0</code>! Now, if we do the little <code>format_ident!</code> dance we did up there:</p> 389<p>We end up with two definitions of <code>T0</code>! Now, if we do the little <code>format_ident!</code> dance we did up there:</p>
390<div class="sourceCode" id="cb33"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb33-1"><a href="#cb33-1"></a><span class="kw">type</span> _add_T0 = <span class="dt">u32</span>;</span> 390<div class="sourceCode" id="cb33"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true"></a><span class="kw">type</span> _add_T0 <span class="op">=</span> <span class="dt">u32</span><span class="op">;</span></span>
391<span id="cb33-2"><a href="#cb33-2"></a><span class="kw">type</span> _add_T1 = <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; _add_T0;</span> 391<span id="cb33-2"><a href="#cb33-2" aria-hidden="true"></a><span class="kw">type</span> _add_T1 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> _add_T0<span class="op">;</span></span>
392<span id="cb33-3"><a href="#cb33-3"></a><span class="kw">fn</span> add( ... ) -&gt; _add_T1 <span class="op">{</span> ... <span class="op">}</span></span> 392<span id="cb33-3"><a href="#cb33-3" aria-hidden="true"></a><span class="kw">fn</span> add( <span class="op">...</span> ) <span class="op">-&gt;</span> _add_T1 <span class="op">{</span> <span class="op">...</span> <span class="op">}</span></span>
393<span id="cb33-4"><a href="#cb33-4"></a></span> 393<span id="cb33-4"><a href="#cb33-4" aria-hidden="true"></a></span>
394<span id="cb33-5"><a href="#cb33-5"></a><span class="kw">type</span> _sub_T0 = <span class="dt">u32</span>;</span> 394<span id="cb33-5"><a href="#cb33-5" aria-hidden="true"></a><span class="kw">type</span> _sub_T0 <span class="op">=</span> <span class="dt">u32</span><span class="op">;</span></span>
395<span id="cb33-6"><a href="#cb33-6"></a><span class="kw">type</span> _sub_T1 = <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; _sub_T0;</span> 395<span id="cb33-6"><a href="#cb33-6" aria-hidden="true"></a><span class="kw">type</span> _sub_T1 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> _sub_T0<span class="op">;</span></span>
396<span id="cb33-7"><a href="#cb33-7"></a><span class="kw">fn</span> sub( ... ) -&gt; _sub_T1 <span class="op">{</span> ... <span class="op">}</span></span></code></pre></div> 396<span id="cb33-7"><a href="#cb33-7" aria-hidden="true"></a><span class="kw">fn</span> sub( <span class="op">...</span> ) <span class="op">-&gt;</span> _sub_T1 <span class="op">{</span> <span class="op">...</span> <span class="op">}</span></span></code></pre></div>
397<p>Voilà! The type aliases don’t tread on each other. Remember to import <code>format_ident</code> from the <code>quote</code> crate.</p> 397<p>Voilà! The type aliases don’t tread on each other. Remember to import <code>format_ident</code> from the <code>quote</code> crate.</p>
398<p><strong>3. The TokenStream Vector</strong></p> 398<p><strong>3. The TokenStream Vector</strong></p>
399<p>We iterate over our types in reverse order (<code>T0</code> is the last return, <code>T1</code> is the second last, so on), assign a number to each iteration with <code>zip</code>, generate type names with <code>format_ident</code>, push a <code>TokenStream</code> with the help of <code>quote</code> and variable interpolation.</p> 399<p>We iterate over our types in reverse order (<code>T0</code> is the last return, <code>T1</code> is the second last, so on), assign a number to each iteration with <code>zip</code>, generate type names with <code>format_ident</code>, push a <code>TokenStream</code> with the help of <code>quote</code> and variable interpolation.</p>
400<p>If you are wondering why we used <code>(1..).zip()</code> instead of <code>.enumerate()</code>, it’s because we wanted to start counting from 1 instead of 0 (we are already done with <code>T0</code>!).</p> 400<p>If you are wondering why we used <code>(1..).zip()</code> instead of <code>.enumerate()</code>, it’s because we wanted to start counting from 1 instead of 0 (we are already done with <code>T0</code>!).</p>
401<h4 id="getting-it-together">Getting it together</h4> 401<h4 id="getting-it-together">Getting it together</h4>
402<p>I promised we’d have a fully working macro by the end of last section. I lied, we have to tie everything together in our <code>generate_curry</code> function:</p> 402<p>I promised we’d have a fully working macro by the end of last section. I lied, we have to tie everything together in our <code>generate_curry</code> function:</p>
403<div class="sourceCode" id="cb34"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb34-1"><a href="#cb34-1"></a><span class="co">// src/lib.rs</span></span> 403<div class="sourceCode" id="cb34"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true"></a><span class="co">// src/lib.rs</span></span>
404<span id="cb34-2"><a href="#cb34-2"></a></span> 404<span id="cb34-2"><a href="#cb34-2" aria-hidden="true"></a></span>
405<span id="cb34-3"><a href="#cb34-3"></a> <span class="kw">fn</span> generate_curry(parsed: ItemFn) -&gt; <span class="pp">proc_macro2::</span>TokenStream <span class="op">{</span></span> 405<span id="cb34-3"><a href="#cb34-3" aria-hidden="true"></a> <span class="kw">fn</span> generate_curry(parsed<span class="op">:</span> ItemFn) <span class="op">-&gt;</span> <span class="pp">proc_macro2::</span>TokenStream <span class="op">{</span></span>
406<span id="cb34-4"><a href="#cb34-4"></a> <span class="kw">let</span> fn_body = parsed.block;</span> 406<span id="cb34-4"><a href="#cb34-4" aria-hidden="true"></a> <span class="kw">let</span> fn_body <span class="op">=</span> parsed<span class="op">.</span>block<span class="op">;</span></span>
407<span id="cb34-5"><a href="#cb34-5"></a> <span class="kw">let</span> sig = parsed.sig;</span> 407<span id="cb34-5"><a href="#cb34-5" aria-hidden="true"></a> <span class="kw">let</span> sig <span class="op">=</span> parsed<span class="op">.</span>sig<span class="op">;</span></span>
408<span id="cb34-6"><a href="#cb34-6"></a> <span class="kw">let</span> vis = parsed.vis;</span> 408<span id="cb34-6"><a href="#cb34-6" aria-hidden="true"></a> <span class="kw">let</span> vis <span class="op">=</span> parsed<span class="op">.</span>vis<span class="op">;</span></span>
409<span id="cb34-7"><a href="#cb34-7"></a> <span class="kw">let</span> fn_name = sig.ident;</span> 409<span id="cb34-7"><a href="#cb34-7" aria-hidden="true"></a> <span class="kw">let</span> fn_name <span class="op">=</span> sig<span class="op">.</span>ident<span class="op">;</span></span>
410<span id="cb34-8"><a href="#cb34-8"></a> <span class="kw">let</span> fn_args = sig.inputs;</span> 410<span id="cb34-8"><a href="#cb34-8" aria-hidden="true"></a> <span class="kw">let</span> fn_args <span class="op">=</span> sig<span class="op">.</span>inputs<span class="op">;</span></span>
411<span id="cb34-9"><a href="#cb34-9"></a> <span class="kw">let</span> fn_return_type = sig.output;</span> 411<span id="cb34-9"><a href="#cb34-9" aria-hidden="true"></a> <span class="kw">let</span> fn_return_type <span class="op">=</span> sig<span class="op">.</span>output<span class="op">;</span></span>
412<span id="cb34-10"><a href="#cb34-10"></a></span> 412<span id="cb34-10"><a href="#cb34-10" aria-hidden="true"></a></span>
413<span id="cb34-11"><a href="#cb34-11"></a> <span class="kw">let</span> arg_idents = extract_arg_idents(fn_args.clone());</span> 413<span id="cb34-11"><a href="#cb34-11" aria-hidden="true"></a> <span class="kw">let</span> arg_idents <span class="op">=</span> extract_arg_idents(fn_args<span class="op">.</span>clone())<span class="op">;</span></span>
414<span id="cb34-12"><a href="#cb34-12"></a> <span class="kw">let</span> first_ident = &amp;arg_idents.first().unwrap();</span> 414<span id="cb34-12"><a href="#cb34-12" aria-hidden="true"></a> <span class="kw">let</span> first_ident <span class="op">=</span> <span class="op">&amp;</span>arg_idents<span class="op">.</span>first()<span class="op">.</span>unwrap()<span class="op">;</span></span>
415<span id="cb34-13"><a href="#cb34-13"></a> <span class="kw">let</span> curried_body = generate_body(&amp;arg_idents<span class="op">[</span><span class="dv">1</span>..<span class="op">]</span>, fn_body.clone());</span> 415<span id="cb34-13"><a href="#cb34-13" aria-hidden="true"></a> <span class="kw">let</span> curried_body <span class="op">=</span> generate_body(<span class="op">&amp;</span>arg_idents[<span class="dv">1</span><span class="op">..</span>]<span class="op">,</span> fn_body<span class="op">.</span>clone())<span class="op">;</span></span>
416<span id="cb34-14"><a href="#cb34-14"></a></span> 416<span id="cb34-14"><a href="#cb34-14" aria-hidden="true"></a></span>
417<span id="cb34-15"><a href="#cb34-15"></a>+ <span class="kw">let</span> arg_types = extract_arg_types(fn_args.clone());</span> 417<span id="cb34-15"><a href="#cb34-15" aria-hidden="true"></a><span class="op">+</span> <span class="kw">let</span> arg_types <span class="op">=</span> extract_arg_types(fn_args<span class="op">.</span>clone())<span class="op">;</span></span>
418<span id="cb34-16"><a href="#cb34-16"></a>+ <span class="kw">let</span> first_type = &amp;arg_types.first().unwrap();</span> 418<span id="cb34-16"><a href="#cb34-16" aria-hidden="true"></a><span class="op">+</span> <span class="kw">let</span> first_type <span class="op">=</span> <span class="op">&amp;</span>arg_types<span class="op">.</span>first()<span class="op">.</span>unwrap()<span class="op">;</span></span>
419<span id="cb34-17"><a href="#cb34-17"></a>+ <span class="kw">let</span> type_aliases = generate_type_aliases(</span> 419<span id="cb34-17"><a href="#cb34-17" aria-hidden="true"></a><span class="op">+</span> <span class="kw">let</span> type_aliases <span class="op">=</span> generate_type_aliases(</span>
420<span id="cb34-18"><a href="#cb34-18"></a>+ &amp;arg_types<span class="op">[</span><span class="dv">1</span>..<span class="op">]</span>,</span> 420<span id="cb34-18"><a href="#cb34-18" aria-hidden="true"></a><span class="op">+</span> <span class="op">&amp;</span>arg_types[<span class="dv">1</span><span class="op">..</span>]<span class="op">,</span></span>
421<span id="cb34-19"><a href="#cb34-19"></a>+ extract_return_type(fn_return_type),</span> 421<span id="cb34-19"><a href="#cb34-19" aria-hidden="true"></a><span class="op">+</span> extract_return_type(fn_return_type)<span class="op">,</span></span>
422<span id="cb34-20"><a href="#cb34-20"></a>+ &amp;fn_name,</span> 422<span id="cb34-20"><a href="#cb34-20" aria-hidden="true"></a><span class="op">+</span> <span class="op">&amp;</span>fn_name<span class="op">,</span></span>
423<span id="cb34-21"><a href="#cb34-21"></a>+ );</span> 423<span id="cb34-21"><a href="#cb34-21" aria-hidden="true"></a><span class="op">+</span> )<span class="op">;</span></span>
424<span id="cb34-22"><a href="#cb34-22"></a></span> 424<span id="cb34-22"><a href="#cb34-22" aria-hidden="true"></a></span>
425<span id="cb34-23"><a href="#cb34-23"></a>+ <span class="kw">let</span> return_type = <span class="pp">format_ident!</span>(<span class="st">&quot;_{}_{}&quot;</span>, &amp;fn_name, <span class="pp">format!</span>(<span class="st">&quot;T{}&quot;</span>, type_aliases.len() - <span class="dv">1</span>));</span> 425<span id="cb34-23"><a href="#cb34-23" aria-hidden="true"></a><span class="op">+</span> <span class="kw">let</span> return_type <span class="op">=</span> <span class="pp">format_ident!</span>(<span class="st">&quot;_{}_{}&quot;</span><span class="op">,</span> <span class="op">&amp;</span>fn_name<span class="op">,</span> <span class="pp">format!</span>(<span class="st">&quot;T{}&quot;</span><span class="op">,</span> type_aliases<span class="op">.</span>len() <span class="op">-</span> <span class="dv">1</span>))<span class="op">;</span></span>
426<span id="cb34-24"><a href="#cb34-24"></a></span> 426<span id="cb34-24"><a href="#cb34-24" aria-hidden="true"></a></span>
427<span id="cb34-25"><a href="#cb34-25"></a>+ <span class="kw">return</span> <span class="pp">quote!</span> <span class="op">{</span></span> 427<span id="cb34-25"><a href="#cb34-25" aria-hidden="true"></a><span class="op">+</span> <span class="kw">return</span> <span class="pp">quote!</span> <span class="op">{</span></span>
428<span id="cb34-26"><a href="#cb34-26"></a>+ #(#type_aliases);* ;</span> 428<span id="cb34-26"><a href="#cb34-26" aria-hidden="true"></a><span class="op">+</span> #(#type_aliases)<span class="op">;*</span> <span class="op">;</span></span>
429<span id="cb34-27"><a href="#cb34-27"></a>+ #vis <span class="kw">fn</span> #fn_name (#first_ident: #first_type) -&gt; #return_type <span class="op">{</span></span> 429<span id="cb34-27"><a href="#cb34-27" aria-hidden="true"></a><span class="op">+</span> #vis <span class="kw">fn</span> #fn_name (#first_ident<span class="op">:</span> #first_type) <span class="op">-&gt;</span> #return_type <span class="op">{</span></span>
430<span id="cb34-28"><a href="#cb34-28"></a>+ #curried_body ;</span> 430<span id="cb34-28"><a href="#cb34-28" aria-hidden="true"></a><span class="op">+</span> #curried_body <span class="op">;</span></span>
431<span id="cb34-29"><a href="#cb34-29"></a>+ <span class="op">}</span></span> 431<span id="cb34-29"><a href="#cb34-29" aria-hidden="true"></a><span class="op">+</span> <span class="op">}</span></span>
432<span id="cb34-30"><a href="#cb34-30"></a>+ <span class="op">}</span>;</span> 432<span id="cb34-30"><a href="#cb34-30" aria-hidden="true"></a><span class="op">+</span> <span class="op">};</span></span>
433<span id="cb34-31"><a href="#cb34-31"></a> <span class="op">}</span></span></code></pre></div> 433<span id="cb34-31"><a href="#cb34-31" aria-hidden="true"></a> <span class="op">}</span></span></code></pre></div>
434<p>Most of the additions are self explanatory, I’ll go through the return statement with you. We are returning a <code>quote!{ ... }</code>, so a <code>proc_macro2::TokenStream</code>. We are iterating through the <code>type_aliases</code> variable, which you might recall, is a <code>Vec&lt;TokenStream&gt;</code>. You might notice the sneaky semicolon before the <code>*</code>. This basically tells <code>quote</code>, to insert an item, then a semicolon, and then the next one, another semicolon, and so on. The semicolon is a separator. We need to manually insert another semicolon at the end of it all, <code>quote</code> doesn’t insert a separator at the end of the iteration.</p> 434<p>Most of the additions are self explanatory, I’ll go through the return statement with you. We are returning a <code>quote!{ ... }</code>, so a <code>proc_macro2::TokenStream</code>. We are iterating through the <code>type_aliases</code> variable, which you might recall, is a <code>Vec&lt;TokenStream&gt;</code>. You might notice the sneaky semicolon before the <code>*</code>. This basically tells <code>quote</code>, to insert an item, then a semicolon, and then the next one, another semicolon, and so on. The semicolon is a separator. We need to manually insert another semicolon at the end of it all, <code>quote</code> doesn’t insert a separator at the end of the iteration.</p>
435<p>We retain the visibility and name of our original function. Our curried function takes as args, just the first argument of our original function. The return type of our curried function is actually, the last type alias we create. If you think back to our manually curried <code>add</code> function, we returned <code>T2</code>, which was in fact, the last type alias we created.</p> 435<p>We retain the visibility and name of our original function. Our curried function takes as args, just the first argument of our original function. The return type of our curried function is actually, the last type alias we create. If you think back to our manually curried <code>add</code> function, we returned <code>T2</code>, which was in fact, the last type alias we created.</p>
436<p>I am sure, at this point, you are itching to test this out, but before that, let me introduce you to some good methods of debugging proc-macro code.</p> 436<p>I am sure, at this point, you are itching to test this out, but before that, let me introduce you to some good methods of debugging proc-macro code.</p>
@@ -462,57 +462,57 @@ fn main() {
462<p>Writing proc-macros without <code>cargo-expand</code> is tantamount to driving a vehicle without rear view mirrors! Keep an eye on what is going on behind your back.</p> 462<p>Writing proc-macros without <code>cargo-expand</code> is tantamount to driving a vehicle without rear view mirrors! Keep an eye on what is going on behind your back.</p>
463<p>Now, your macro won’t always compile, you might just recieve the bee movie script as an error. <code>cargo-expand</code> will not work in such cases. I would suggest printing out your variables to inspect them. <code>TokenStream</code> implements <code>Display</code> as well as <code>Debug</code>. We don’t always have to be respectable programmers. Just print it.</p> 463<p>Now, your macro won’t always compile, you might just recieve the bee movie script as an error. <code>cargo-expand</code> will not work in such cases. I would suggest printing out your variables to inspect them. <code>TokenStream</code> implements <code>Display</code> as well as <code>Debug</code>. We don’t always have to be respectable programmers. Just print it.</p>
464<p>Enough of that, lets get testing:</p> 464<p>Enough of that, lets get testing:</p>
465<div class="sourceCode" id="cb37"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb37-1"><a href="#cb37-1"></a><span class="co">// tests/smoke.rs</span></span> 465<div class="sourceCode" id="cb37"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true"></a><span class="co">// tests/smoke.rs</span></span>
466<span id="cb37-2"><a href="#cb37-2"></a></span> 466<span id="cb37-2"><a href="#cb37-2" aria-hidden="true"></a></span>
467<span id="cb37-3"><a href="#cb37-3"></a><span class="at">#![</span>feature<span class="at">(</span>type_alias_impl_trait<span class="at">)]</span></span> 467<span id="cb37-3"><a href="#cb37-3" aria-hidden="true"></a><span class="at">#![</span>feature<span class="at">(</span>type_alias_impl_trait<span class="at">)]</span></span>
468<span id="cb37-4"><a href="#cb37-4"></a></span> 468<span id="cb37-4"><a href="#cb37-4" aria-hidden="true"></a></span>
469<span id="cb37-5"><a href="#cb37-5"></a><span class="at">#[</span><span class="pp">crate_name::</span>curry<span class="at">]</span></span> 469<span id="cb37-5"><a href="#cb37-5" aria-hidden="true"></a><span class="at">#[</span><span class="pp">crate_name::</span>curry<span class="at">]</span></span>
470<span id="cb37-6"><a href="#cb37-6"></a><span class="kw">fn</span> add(x: <span class="dt">u32</span>, y: <span class="dt">u32</span>, z: <span class="dt">u32</span>) -&gt; <span class="dt">u32</span> <span class="op">{</span></span> 470<span id="cb37-6"><a href="#cb37-6" aria-hidden="true"></a><span class="kw">fn</span> add(x<span class="op">:</span> <span class="dt">u32</span><span class="op">,</span> y<span class="op">:</span> <span class="dt">u32</span><span class="op">,</span> z<span class="op">:</span> <span class="dt">u32</span>) <span class="op">-&gt;</span> <span class="dt">u32</span> <span class="op">{</span></span>
471<span id="cb37-7"><a href="#cb37-7"></a> x + y + z</span> 471<span id="cb37-7"><a href="#cb37-7" aria-hidden="true"></a> x <span class="op">+</span> y <span class="op">+</span> z</span>
472<span id="cb37-8"><a href="#cb37-8"></a><span class="op">}</span></span> 472<span id="cb37-8"><a href="#cb37-8" aria-hidden="true"></a><span class="op">}</span></span>
473<span id="cb37-9"><a href="#cb37-9"></a></span> 473<span id="cb37-9"><a href="#cb37-9" aria-hidden="true"></a></span>
474<span id="cb37-10"><a href="#cb37-10"></a><span class="at">#[</span>test<span class="at">]</span></span> 474<span id="cb37-10"><a href="#cb37-10" aria-hidden="true"></a><span class="at">#[</span>test<span class="at">]</span></span>
475<span id="cb37-11"><a href="#cb37-11"></a><span class="kw">fn</span> works() <span class="op">{</span></span> 475<span id="cb37-11"><a href="#cb37-11" aria-hidden="true"></a><span class="kw">fn</span> works() <span class="op">{</span></span>
476<span id="cb37-12"><a href="#cb37-12"></a> <span class="pp">assert_eq!</span>(<span class="dv">15</span>, add(<span class="dv">4</span>)(<span class="dv">5</span>)(<span class="dv">6</span>));</span> 476<span id="cb37-12"><a href="#cb37-12" aria-hidden="true"></a> <span class="pp">assert_eq!</span>(<span class="dv">15</span><span class="op">,</span> add(<span class="dv">4</span>)(<span class="dv">5</span>)(<span class="dv">6</span>))<span class="op">;</span></span>
477<span id="cb37-13"><a href="#cb37-13"></a><span class="op">}</span></span></code></pre></div> 477<span id="cb37-13"><a href="#cb37-13" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
478<p>Run <code>cargo +nightly test</code>. You should see a pleasing message:</p> 478<p>Run <code>cargo +nightly test</code>. You should see a pleasing message:</p>
479<pre><code>running 1 test 479<pre><code>running 1 test
480test tests::works ... ok</code></pre> 480test tests::works ... ok</code></pre>
481<p>Take a look at the expansion for our curry macro, via <code>cargo +nightly expand --tests smoke</code>:</p> 481<p>Take a look at the expansion for our curry macro, via <code>cargo +nightly expand --tests smoke</code>:</p>
482<div class="sourceCode" id="cb39"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb39-1"><a href="#cb39-1"></a><span class="kw">type</span> _add_T0 = <span class="dt">u32</span>;</span> 482<div class="sourceCode" id="cb39"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb39-1"><a href="#cb39-1" aria-hidden="true"></a><span class="kw">type</span> _add_T0 <span class="op">=</span> <span class="dt">u32</span><span class="op">;</span></span>
483<span id="cb39-2"><a href="#cb39-2"></a><span class="kw">type</span> _add_T1 = <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; _add_T0;</span> 483<span id="cb39-2"><a href="#cb39-2" aria-hidden="true"></a><span class="kw">type</span> _add_T1 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> _add_T0<span class="op">;</span></span>
484<span id="cb39-3"><a href="#cb39-3"></a><span class="kw">type</span> _add_T2 = <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) -&gt; _add_T1;</span> 484<span id="cb39-3"><a href="#cb39-3" aria-hidden="true"></a><span class="kw">type</span> _add_T2 <span class="op">=</span> <span class="kw">impl</span> <span class="bu">Fn</span>(<span class="dt">u32</span>) <span class="op">-&gt;</span> _add_T1<span class="op">;</span></span>
485<span id="cb39-4"><a href="#cb39-4"></a><span class="kw">fn</span> add(x: <span class="dt">u32</span>) -&gt; _add_T2 <span class="op">{</span></span> 485<span id="cb39-4"><a href="#cb39-4" aria-hidden="true"></a><span class="kw">fn</span> add(x<span class="op">:</span> <span class="dt">u32</span>) <span class="op">-&gt;</span> _add_T2 <span class="op">{</span></span>
486<span id="cb39-5"><a href="#cb39-5"></a> <span class="kw">return</span> (<span class="kw">move</span> |y| <span class="op">{</span></span> 486<span id="cb39-5"><a href="#cb39-5" aria-hidden="true"></a> <span class="kw">return</span> (<span class="kw">move</span> <span class="op">|</span>y<span class="op">|</span> <span class="op">{</span></span>
487<span id="cb39-6"><a href="#cb39-6"></a> <span class="kw">move</span> |z| <span class="op">{</span></span> 487<span id="cb39-6"><a href="#cb39-6" aria-hidden="true"></a> <span class="kw">move</span> <span class="op">|</span>z<span class="op">|</span> <span class="op">{</span></span>
488<span id="cb39-7"><a href="#cb39-7"></a> <span class="kw">return</span> x + y + z;</span> 488<span id="cb39-7"><a href="#cb39-7" aria-hidden="true"></a> <span class="kw">return</span> x <span class="op">+</span> y <span class="op">+</span> z<span class="op">;</span></span>
489<span id="cb39-8"><a href="#cb39-8"></a> <span class="op">}</span></span> 489<span id="cb39-8"><a href="#cb39-8" aria-hidden="true"></a> <span class="op">}</span></span>
490<span id="cb39-9"><a href="#cb39-9"></a> <span class="op">}</span>);</span> 490<span id="cb39-9"><a href="#cb39-9" aria-hidden="true"></a> <span class="op">}</span>)<span class="op">;</span></span>
491<span id="cb39-10"><a href="#cb39-10"></a><span class="op">}</span></span> 491<span id="cb39-10"><a href="#cb39-10" aria-hidden="true"></a><span class="op">}</span></span>
492<span id="cb39-11"><a href="#cb39-11"></a></span> 492<span id="cb39-11"><a href="#cb39-11" aria-hidden="true"></a></span>
493<span id="cb39-12"><a href="#cb39-12"></a><span class="co">// a bunch of other stuff generated by #[test] and assert_eq!</span></span></code></pre></div> 493<span id="cb39-12"><a href="#cb39-12" aria-hidden="true"></a><span class="co">// a bunch of other stuff generated by #[test] and assert_eq!</span></span></code></pre></div>
494<p>A sight for sore eyes.</p> 494<p>A sight for sore eyes.</p>
495<p>Here is a more complex example that generates ten multiples of the first ten natural numbers:</p> 495<p>Here is a more complex example that generates ten multiples of the first ten natural numbers:</p>
496<div class="sourceCode" id="cb40"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb40-1"><a href="#cb40-1"></a><span class="at">#[</span>curry<span class="at">]</span></span> 496<div class="sourceCode" id="cb40"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true"></a><span class="at">#[</span>curry<span class="at">]</span></span>
497<span id="cb40-2"><a href="#cb40-2"></a><span class="kw">fn</span> product(x: <span class="dt">u32</span>, y: <span class="dt">u32</span>) -&gt; <span class="dt">u32</span> <span class="op">{</span></span> 497<span id="cb40-2"><a href="#cb40-2" aria-hidden="true"></a><span class="kw">fn</span> product(x<span class="op">:</span> <span class="dt">u32</span><span class="op">,</span> y<span class="op">:</span> <span class="dt">u32</span>) <span class="op">-&gt;</span> <span class="dt">u32</span> <span class="op">{</span></span>
498<span id="cb40-3"><a href="#cb40-3"></a> x * y</span> 498<span id="cb40-3"><a href="#cb40-3" aria-hidden="true"></a> x <span class="op">*</span> y</span>
499<span id="cb40-4"><a href="#cb40-4"></a><span class="op">}</span></span> 499<span id="cb40-4"><a href="#cb40-4" aria-hidden="true"></a><span class="op">}</span></span>
500<span id="cb40-5"><a href="#cb40-5"></a></span> 500<span id="cb40-5"><a href="#cb40-5" aria-hidden="true"></a></span>
501<span id="cb40-6"><a href="#cb40-6"></a><span class="kw">fn</span> multiples() -&gt; <span class="dt">Vec</span>&lt;<span class="dt">Vec</span>&lt;<span class="dt">u32</span>&gt;&gt;<span class="op">{</span></span> 501<span id="cb40-6"><a href="#cb40-6" aria-hidden="true"></a><span class="kw">fn</span> multiples() <span class="op">-&gt;</span> <span class="dt">Vec</span><span class="op">&lt;</span><span class="dt">Vec</span><span class="op">&lt;</span><span class="dt">u32</span><span class="op">&gt;&gt;{</span></span>
502<span id="cb40-7"><a href="#cb40-7"></a> <span class="kw">let</span> v = (<span class="dv">1</span>..=<span class="dv">10</span>).map(product);</span> 502<span id="cb40-7"><a href="#cb40-7" aria-hidden="true"></a> <span class="kw">let</span> v <span class="op">=</span> (<span class="dv">1</span><span class="op">..=</span><span class="dv">10</span>)<span class="op">.</span>map(product)<span class="op">;</span></span>
503<span id="cb40-8"><a href="#cb40-8"></a> <span class="kw">return</span> (<span class="dv">1</span>..=<span class="dv">10</span>)</span> 503<span id="cb40-8"><a href="#cb40-8" aria-hidden="true"></a> <span class="kw">return</span> (<span class="dv">1</span><span class="op">..=</span><span class="dv">10</span>)</span>
504<span id="cb40-9"><a href="#cb40-9"></a> .map(|x| v.clone().map(|f| f(x)).collect())</span> 504<span id="cb40-9"><a href="#cb40-9" aria-hidden="true"></a> <span class="op">.</span>map(<span class="op">|</span>x<span class="op">|</span> v<span class="op">.</span>clone()<span class="op">.</span>map(<span class="op">|</span>f<span class="op">|</span> f(x))<span class="op">.</span>collect())</span>
505<span id="cb40-10"><a href="#cb40-10"></a> .collect();</span> 505<span id="cb40-10"><a href="#cb40-10" aria-hidden="true"></a> <span class="op">.</span>collect()<span class="op">;</span></span>
506<span id="cb40-11"><a href="#cb40-11"></a><span class="op">}</span></span></code></pre></div> 506<span id="cb40-11"><a href="#cb40-11" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
507<h3 id="notes">Notes</h3> 507<h3 id="notes">Notes</h3>
508<p>I didn’t quite explain why we use <code>move |arg|</code> in our closure. This is because we want to take ownership of the variable supplied to us. Take a look at this example:</p> 508<p>I didn’t quite explain why we use <code>move |arg|</code> in our closure. This is because we want to take ownership of the variable supplied to us. Take a look at this example:</p>
509<div class="sourceCode" id="cb41"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb41-1"><a href="#cb41-1"></a><span class="kw">let</span> v = add(<span class="dv">5</span>);</span> 509<div class="sourceCode" id="cb41"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb41-1"><a href="#cb41-1" aria-hidden="true"></a><span class="kw">let</span> v <span class="op">=</span> add(<span class="dv">5</span>)<span class="op">;</span></span>
510<span id="cb41-2"><a href="#cb41-2"></a><span class="kw">let</span> g;</span> 510<span id="cb41-2"><a href="#cb41-2" aria-hidden="true"></a><span class="kw">let</span> g<span class="op">;</span></span>
511<span id="cb41-3"><a href="#cb41-3"></a><span class="op">{</span></span> 511<span id="cb41-3"><a href="#cb41-3" aria-hidden="true"></a><span class="op">{</span></span>
512<span id="cb41-4"><a href="#cb41-4"></a> <span class="kw">let</span> x = <span class="dv">5</span>;</span> 512<span id="cb41-4"><a href="#cb41-4" aria-hidden="true"></a> <span class="kw">let</span> x <span class="op">=</span> <span class="dv">5</span><span class="op">;</span></span>
513<span id="cb41-5"><a href="#cb41-5"></a> g = v(x);</span> 513<span id="cb41-5"><a href="#cb41-5" aria-hidden="true"></a> g <span class="op">=</span> v(x)<span class="op">;</span></span>
514<span id="cb41-6"><a href="#cb41-6"></a><span class="op">}</span></span> 514<span id="cb41-6"><a href="#cb41-6" aria-hidden="true"></a><span class="op">}</span></span>
515<span id="cb41-7"><a href="#cb41-7"></a><span class="pp">println!</span>(<span class="st">&quot;{}&quot;</span>, g(<span class="dv">2</span>));</span></code></pre></div> 515<span id="cb41-7"><a href="#cb41-7" aria-hidden="true"></a><span class="pp">println!</span>(<span class="st">&quot;{}&quot;</span><span class="op">,</span> g(<span class="dv">2</span>))<span class="op">;</span></span></code></pre></div>
516<p>Variable <code>x</code> goes out of scope before <code>g</code> can return a concrete value. If we take ownership of <code>x</code> by <code>move</code>ing it into our closure, we can expect this to work reliably. In fact, rustc understands this, and forces you to use <code>move</code>.</p> 516<p>Variable <code>x</code> goes out of scope before <code>g</code> can return a concrete value. If we take ownership of <code>x</code> by <code>move</code>ing it into our closure, we can expect this to work reliably. In fact, rustc understands this, and forces you to use <code>move</code>.</p>
517<p>This usage of <code>move</code> is exactly why <strong>a curried function without a return is useless</strong>. Every variable we pass to our curried function gets moved into its local scope. Playing with these variables cannot cause a change outside this scope. Returning is our only method of interaction with anything beyond this function.</p> 517<p>This usage of <code>move</code> is exactly why <strong>a curried function without a return is useless</strong>. Every variable we pass to our curried function gets moved into its local scope. Playing with these variables cannot cause a change outside this scope. Returning is our only method of interaction with anything beyond this function.</p>
518<h3 id="conclusion">Conclusion</h3> 518<h3 id="conclusion">Conclusion</h3>
@@ -538,7 +538,10 @@ test tests::works ... ok</code></pre>
538 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 538 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
539 <p> 539 <p>
540 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 540 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
541 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 541 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
542 I also design fonts:
543 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
544 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
542 </p> 545 </p>
543 <p>Send me a mail at [email protected] or a message at [email protected].</p> 546 <p>Send me a mail at [email protected] or a message at [email protected].</p>
544 </div> 547 </div>
diff --git a/docs/posts/bash_harder_with_vim/index.html b/docs/posts/bash_harder_with_vim/index.html
index 303880d..257f717 100644
--- a/docs/posts/bash_harder_with_vim/index.html
+++ b/docs/posts/bash_harder_with_vim/index.html
@@ -84,7 +84,10 @@ Press ENTER or type command to continue</code></pre>
84 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 84 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
85 <p> 85 <p>
86 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 86 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
87 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 87 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
88 I also design fonts:
89 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
90 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
88 </p> 91 </p>
89 <p>Send me a mail at [email protected] or a message at [email protected].</p> 92 <p>Send me a mail at [email protected] or a message at [email protected].</p>
90 </div> 93 </div>
diff --git a/docs/posts/bye_bye_BDFs/index.html b/docs/posts/bye_bye_BDFs/index.html
index 43d2dfd..0719ae5 100644
--- a/docs/posts/bye_bye_BDFs/index.html
+++ b/docs/posts/bye_bye_BDFs/index.html
@@ -56,7 +56,10 @@
56 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 56 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
57 <p> 57 <p>
58 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 58 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
59 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 59 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
60 I also design fonts:
61 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
62 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
60 </p> 63 </p>
61 <p>Send me a mail at [email protected] or a message at [email protected].</p> 64 <p>Send me a mail at [email protected] or a message at [email protected].</p>
62 </div> 65 </div>
diff --git a/docs/posts/call_to_ARMs/index.html b/docs/posts/call_to_ARMs/index.html
index a05ed38..3226cdd 100644
--- a/docs/posts/call_to_ARMs/index.html
+++ b/docs/posts/call_to_ARMs/index.html
@@ -81,7 +81,10 @@ Reading symbols from main... # yay!</code></pre>
81 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 81 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
82 <p> 82 <p>
83 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 83 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
84 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 84 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
85 I also design fonts:
86 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
87 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
85 </p> 88 </p>
86 <p>Send me a mail at [email protected] or a message at [email protected].</p> 89 <p>Send me a mail at [email protected] or a message at [email protected].</p>
87 </div> 90 </div>
diff --git a/docs/posts/color_conundrum/index.html b/docs/posts/color_conundrum/index.html
index c7db8cd..e6412a0 100644
--- a/docs/posts/color_conundrum/index.html
+++ b/docs/posts/color_conundrum/index.html
@@ -58,7 +58,10 @@
58 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 58 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
59 <p> 59 <p>
60 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 60 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
61 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 61 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
62 I also design fonts:
63 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
64 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
62 </p> 65 </p>
63 <p>Send me a mail at [email protected] or a message at [email protected].</p> 66 <p>Send me a mail at [email protected] or a message at [email protected].</p>
64 </div> 67 </div>
diff --git a/docs/posts/font_size_fallacies/index.html b/docs/posts/font_size_fallacies/index.html
index af55661..41b6b36 100644
--- a/docs/posts/font_size_fallacies/index.html
+++ b/docs/posts/font_size_fallacies/index.html
@@ -80,7 +80,10 @@ Dimensions: 1920x1080 @ 13&quot; (29.5x16.5 sq. cm)
80 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 80 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
81 <p> 81 <p>
82 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 82 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
83 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 83 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
84 I also design fonts:
85 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
86 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
84 </p> 87 </p>
85 <p>Send me a mail at [email protected] or a message at [email protected].</p> 88 <p>Send me a mail at [email protected] or a message at [email protected].</p>
86 </div> 89 </div>
diff --git a/docs/posts/get_better_at_yanking_and_putting_in_vim/index.html b/docs/posts/get_better_at_yanking_and_putting_in_vim/index.html
index 5d42ee6..d0251d2 100644
--- a/docs/posts/get_better_at_yanking_and_putting_in_vim/index.html
+++ b/docs/posts/get_better_at_yanking_and_putting_in_vim/index.html
@@ -67,7 +67,10 @@ nnoremap gb `[v`] &quot; &quot;a quick map to perform the above</code></pre><
67 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 67 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
68 <p> 68 <p>
69 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 69 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
70 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 70 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
71 I also design fonts:
72 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
73 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
71 </p> 74 </p>
72 <p>Send me a mail at [email protected] or a message at [email protected].</p> 75 <p>Send me a mail at [email protected] or a message at [email protected].</p>
73 </div> 76 </div>
diff --git a/docs/posts/gripes_with_go/index.html b/docs/posts/gripes_with_go/index.html
index 4d37038..fdfaf93 100644
--- a/docs/posts/gripes_with_go/index.html
+++ b/docs/posts/gripes_with_go/index.html
@@ -50,101 +50,101 @@
50<h3 id="lack-of-sum-types">Lack of Sum types</h3> 50<h3 id="lack-of-sum-types">Lack of Sum types</h3>
51<p>A “Sum” type is a data type that can hold one of many states at a given time, similar to how a boolean can hold a true or a false, not too different from an <code>enum</code> type in C. Go lacks <code>enum</code> types unfortunately, and you are forced to resort to crafting your own substitute.</p> 51<p>A “Sum” type is a data type that can hold one of many states at a given time, similar to how a boolean can hold a true or a false, not too different from an <code>enum</code> type in C. Go lacks <code>enum</code> types unfortunately, and you are forced to resort to crafting your own substitute.</p>
52<p>A type to represent gender for example:</p> 52<p>A type to represent gender for example:</p>
53<div class="sourceCode" id="cb1"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb1-1"><a href="#cb1-1"></a><span class="kw">type</span> Gender <span class="dt">int</span></span> 53<div class="sourceCode" id="cb1"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true"></a><span class="kw">type</span> Gender <span class="dt">int</span></span>
54<span id="cb1-2"><a href="#cb1-2"></a></span> 54<span id="cb1-2"><a href="#cb1-2" aria-hidden="true"></a></span>
55<span id="cb1-3"><a href="#cb1-3"></a><span class="kw">const</span> (</span> 55<span id="cb1-3"><a href="#cb1-3" aria-hidden="true"></a><span class="kw">const</span> (</span>
56<span id="cb1-4"><a href="#cb1-4"></a> Male Gender = <span class="ot">iota</span> <span class="co">// assigns Male to 0</span></span> 56<span id="cb1-4"><a href="#cb1-4" aria-hidden="true"></a> Male Gender = <span class="ot">iota</span> <span class="co">// assigns Male to 0</span></span>
57<span id="cb1-5"><a href="#cb1-5"></a> Female <span class="co">// assigns Female to 1</span></span> 57<span id="cb1-5"><a href="#cb1-5" aria-hidden="true"></a> Female <span class="co">// assigns Female to 1</span></span>
58<span id="cb1-6"><a href="#cb1-6"></a> Other <span class="co">// assigns Other to 2</span></span> 58<span id="cb1-6"><a href="#cb1-6" aria-hidden="true"></a> Other <span class="co">// assigns Other to 2</span></span>
59<span id="cb1-7"><a href="#cb1-7"></a>)</span> 59<span id="cb1-7"><a href="#cb1-7" aria-hidden="true"></a>)</span>
60<span id="cb1-8"><a href="#cb1-8"></a></span> 60<span id="cb1-8"><a href="#cb1-8" aria-hidden="true"></a></span>
61<span id="cb1-9"><a href="#cb1-9"></a>fmt.Println(<span class="st">&quot;My gender is &quot;</span>, Male)</span> 61<span id="cb1-9"><a href="#cb1-9" aria-hidden="true"></a>fmt.Println(<span class="st">&quot;My gender is &quot;</span>, Male)</span>
62<span id="cb1-10"><a href="#cb1-10"></a><span class="co">// My gender is 0</span></span> 62<span id="cb1-10"><a href="#cb1-10" aria-hidden="true"></a><span class="co">// My gender is 0</span></span>
63<span id="cb1-11"><a href="#cb1-11"></a><span class="co">// Oops! We have to implement String() for Gender ...</span></span> 63<span id="cb1-11"><a href="#cb1-11" aria-hidden="true"></a><span class="co">// Oops! We have to implement String() for Gender ...</span></span>
64<span id="cb1-12"><a href="#cb1-12"></a></span> 64<span id="cb1-12"><a href="#cb1-12" aria-hidden="true"></a></span>
65<span id="cb1-13"><a href="#cb1-13"></a><span class="kw">func</span> (g Gender) String() <span class="dt">string</span> {</span> 65<span id="cb1-13"><a href="#cb1-13" aria-hidden="true"></a><span class="kw">func</span> (g Gender) String() <span class="dt">string</span> {</span>
66<span id="cb1-14"><a href="#cb1-14"></a> <span class="kw">switch</span> (g) {</span> 66<span id="cb1-14"><a href="#cb1-14" aria-hidden="true"></a> <span class="kw">switch</span> (g) {</span>
67<span id="cb1-15"><a href="#cb1-15"></a> <span class="kw">case</span> <span class="dv">0</span>: <span class="kw">return</span> <span class="st">&quot;Male&quot;</span></span> 67<span id="cb1-15"><a href="#cb1-15" aria-hidden="true"></a> <span class="kw">case</span> <span class="dv">0</span>: <span class="kw">return</span> <span class="st">&quot;Male&quot;</span></span>
68<span id="cb1-16"><a href="#cb1-16"></a> <span class="kw">case</span> <span class="dv">1</span>: <span class="kw">return</span> <span class="st">&quot;Female&quot;</span></span> 68<span id="cb1-16"><a href="#cb1-16" aria-hidden="true"></a> <span class="kw">case</span> <span class="dv">1</span>: <span class="kw">return</span> <span class="st">&quot;Female&quot;</span></span>
69<span id="cb1-17"><a href="#cb1-17"></a> <span class="kw">default</span>: <span class="kw">return</span> <span class="st">&quot;Other&quot;</span></span> 69<span id="cb1-17"><a href="#cb1-17" aria-hidden="true"></a> <span class="kw">default</span>: <span class="kw">return</span> <span class="st">&quot;Other&quot;</span></span>
70<span id="cb1-18"><a href="#cb1-18"></a> }</span> 70<span id="cb1-18"><a href="#cb1-18" aria-hidden="true"></a> }</span>
71<span id="cb1-19"><a href="#cb1-19"></a>}</span> 71<span id="cb1-19"><a href="#cb1-19" aria-hidden="true"></a>}</span>
72<span id="cb1-20"><a href="#cb1-20"></a></span> 72<span id="cb1-20"><a href="#cb1-20" aria-hidden="true"></a></span>
73<span id="cb1-21"><a href="#cb1-21"></a><span class="co">// You can accidentally do stupid stuff like:</span></span> 73<span id="cb1-21"><a href="#cb1-21" aria-hidden="true"></a><span class="co">// You can accidentally do stupid stuff like:</span></span>
74<span id="cb1-22"><a href="#cb1-22"></a>gender := Male + <span class="dv">1</span></span></code></pre></div> 74<span id="cb1-22"><a href="#cb1-22" aria-hidden="true"></a>gender := Male + <span class="dv">1</span></span></code></pre></div>
75<p>The Haskell equivalent of the same:</p> 75<p>The Haskell equivalent of the same:</p>
76<div class="sourceCode" id="cb2"><pre class="sourceCode haskell"><code class="sourceCode haskell"><span id="cb2-1"><a href="#cb2-1"></a><span class="kw">data</span> <span class="dt">Gender</span> <span class="ot">=</span> <span class="dt">Male</span></span> 76<div class="sourceCode" id="cb2"><pre class="sourceCode haskell"><code class="sourceCode haskell"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true"></a><span class="kw">data</span> <span class="dt">Gender</span> <span class="ot">=</span> <span class="dt">Male</span></span>
77<span id="cb2-2"><a href="#cb2-2"></a> <span class="op">|</span> <span class="dt">Female</span></span> 77<span id="cb2-2"><a href="#cb2-2" aria-hidden="true"></a> <span class="op">|</span> <span class="dt">Female</span></span>
78<span id="cb2-3"><a href="#cb2-3"></a> <span class="op">|</span> <span class="dt">Other</span></span> 78<span id="cb2-3"><a href="#cb2-3" aria-hidden="true"></a> <span class="op">|</span> <span class="dt">Other</span></span>
79<span id="cb2-4"><a href="#cb2-4"></a> <span class="kw">deriving</span> (<span class="dt">Show</span>)</span> 79<span id="cb2-4"><a href="#cb2-4" aria-hidden="true"></a> <span class="kw">deriving</span> (<span class="dt">Show</span>)</span>
80<span id="cb2-5"><a href="#cb2-5"></a></span> 80<span id="cb2-5"><a href="#cb2-5" aria-hidden="true"></a></span>
81<span id="cb2-6"><a href="#cb2-6"></a><span class="fu">print</span> <span class="op">$</span> <span class="st">&quot;My gender is &quot;</span> <span class="op">++</span> (<span class="fu">show</span> <span class="dt">Male</span>)</span></code></pre></div> 81<span id="cb2-6"><a href="#cb2-6" aria-hidden="true"></a><span class="fu">print</span> <span class="op">$</span> <span class="st">&quot;My gender is &quot;</span> <span class="op">++</span> (<span class="fu">show</span> <span class="dt">Male</span>)</span></code></pre></div>
82<h3 id="type-assertions">Type Assertions</h3> 82<h3 id="type-assertions">Type Assertions</h3>
83<p>A downcast with an optional error check? What could go wrong?</p> 83<p>A downcast with an optional error check? What could go wrong?</p>
84<p>Type assertions in Go allow you to do:</p> 84<p>Type assertions in Go allow you to do:</p>
85<div class="sourceCode" id="cb3"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb3-1"><a href="#cb3-1"></a><span class="kw">var</span> x <span class="kw">interface</span>{} = <span class="dv">7</span></span> 85<div class="sourceCode" id="cb3"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true"></a><span class="kw">var</span> x <span class="kw">interface</span>{} = <span class="dv">7</span></span>
86<span id="cb3-2"><a href="#cb3-2"></a>y, goodToGo := x.(<span class="dt">int</span>)</span> 86<span id="cb3-2"><a href="#cb3-2" aria-hidden="true"></a>y, goodToGo := x.(<span class="dt">int</span>)</span>
87<span id="cb3-3"><a href="#cb3-3"></a><span class="kw">if</span> goodToGo {</span> 87<span id="cb3-3"><a href="#cb3-3" aria-hidden="true"></a><span class="kw">if</span> goodToGo {</span>
88<span id="cb3-4"><a href="#cb3-4"></a> fmt.Println(y)</span> 88<span id="cb3-4"><a href="#cb3-4" aria-hidden="true"></a> fmt.Println(y)</span>
89<span id="cb3-5"><a href="#cb3-5"></a>}</span></code></pre></div> 89<span id="cb3-5"><a href="#cb3-5" aria-hidden="true"></a>}</span></code></pre></div>
90<p>The error check however is optional:</p> 90<p>The error check however is optional:</p>
91<div class="sourceCode" id="cb4"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb4-1"><a href="#cb4-1"></a><span class="kw">var</span> x <span class="kw">interface</span>{} = <span class="dv">7</span></span> 91<div class="sourceCode" id="cb4"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true"></a><span class="kw">var</span> x <span class="kw">interface</span>{} = <span class="dv">7</span></span>
92<span id="cb4-2"><a href="#cb4-2"></a><span class="kw">var</span> y := x.(<span class="dt">float64</span>)</span> 92<span id="cb4-2"><a href="#cb4-2" aria-hidden="true"></a><span class="kw">var</span> y := x.(<span class="dt">float64</span>)</span>
93<span id="cb4-3"><a href="#cb4-3"></a>fmt.Println(y)</span> 93<span id="cb4-3"><a href="#cb4-3" aria-hidden="true"></a>fmt.Println(y)</span>
94<span id="cb4-4"><a href="#cb4-4"></a><span class="co">// results in a runtime error:</span></span> 94<span id="cb4-4"><a href="#cb4-4" aria-hidden="true"></a><span class="co">// results in a runtime error:</span></span>
95<span id="cb4-5"><a href="#cb4-5"></a><span class="co">// panic: interface conversion: interface {} is int, not float64</span></span></code></pre></div> 95<span id="cb4-5"><a href="#cb4-5" aria-hidden="true"></a><span class="co">// panic: interface conversion: interface {} is int, not float64</span></span></code></pre></div>
96<h3 id="date-and-time">Date and Time</h3> 96<h3 id="date-and-time">Date and Time</h3>
97<p>Anyone that has written Go previously, will probably already know what I am getting at here. For the uninitiated, parsing and formatting dates in Go requires a “layout”. This “layout” is based on magical reference date:</p> 97<p>Anyone that has written Go previously, will probably already know what I am getting at here. For the uninitiated, parsing and formatting dates in Go requires a “layout”. This “layout” is based on magical reference date:</p>
98<pre><code>Mon Jan 2 15:04:05 MST 2006</code></pre> 98<pre><code>Mon Jan 2 15:04:05 MST 2006</code></pre>
99<p>Which is the date produced when you write the first seven natural numbers like so:</p> 99<p>Which is the date produced when you write the first seven natural numbers like so:</p>
100<pre><code>01/02 03:04:05 &#39;06 -0700</code></pre> 100<pre><code>01/02 03:04:05 &#39;06 -0700</code></pre>
101<p>Parsing a string in <code>YYYY-MM-DD</code> format would look something like:</p> 101<p>Parsing a string in <code>YYYY-MM-DD</code> format would look something like:</p>
102<div class="sourceCode" id="cb7"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb7-1"><a href="#cb7-1"></a><span class="kw">const</span> layout = <span class="st">&quot;2006-01-02&quot;</span></span> 102<div class="sourceCode" id="cb7"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true"></a><span class="kw">const</span> layout = <span class="st">&quot;2006-01-02&quot;</span></span>
103<span id="cb7-2"><a href="#cb7-2"></a>time.Parse(layout, <span class="st">&quot;2020-08-01&quot;</span>)</span></code></pre></div> 103<span id="cb7-2"><a href="#cb7-2" aria-hidden="true"></a>time.Parse(layout, <span class="st">&quot;2020-08-01&quot;</span>)</span></code></pre></div>
104<p>This so-called “intuitive” method of formatting dates doesn’t allow you to print <code>0000 hrs</code> as <code>2400 hrs</code>, it doesn’t allow you to omit the leading zero in 24 hour formats. It is rife with inconveniences, if only there were a <a href="https://man7.org/linux/man-pages/man3/strftime.3.html">tried and tested</a> date formatting convention …</p> 104<p>This so-called “intuitive” method of formatting dates doesn’t allow you to print <code>0000 hrs</code> as <code>2400 hrs</code>, it doesn’t allow you to omit the leading zero in 24 hour formats. It is rife with inconveniences, if only there were a <a href="https://man7.org/linux/man-pages/man3/strftime.3.html">tried and tested</a> date formatting convention …</p>
105<h3 id="statements-over-expressions">Statements over Expressions</h3> 105<h3 id="statements-over-expressions">Statements over Expressions</h3>
106<p>Statements have side effects, expressions return values. More often than not, expressions are easier to understand at a glance: evaluate the LHS and assign the same to the RHS.</p> 106<p>Statements have side effects, expressions return values. More often than not, expressions are easier to understand at a glance: evaluate the LHS and assign the same to the RHS.</p>
107<p>Rust allows you to create local namespaces, and treats blocks (<code>{}</code>) as expressions:</p> 107<p>Rust allows you to create local namespaces, and treats blocks (<code>{}</code>) as expressions:</p>
108<div class="sourceCode" id="cb8"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb8-1"><a href="#cb8-1"></a><span class="kw">let</span> twenty_seven = <span class="op">{</span></span> 108<div class="sourceCode" id="cb8"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true"></a><span class="kw">let</span> twenty_seven <span class="op">=</span> <span class="op">{</span></span>
109<span id="cb8-2"><a href="#cb8-2"></a> <span class="kw">let</span> three = <span class="dv">1</span> + <span class="dv">2</span>;</span> 109<span id="cb8-2"><a href="#cb8-2" aria-hidden="true"></a> <span class="kw">let</span> three <span class="op">=</span> <span class="dv">1</span> <span class="op">+</span> <span class="dv">2</span><span class="op">;</span></span>
110<span id="cb8-3"><a href="#cb8-3"></a> <span class="kw">let</span> nine = three * three;</span> 110<span id="cb8-3"><a href="#cb8-3" aria-hidden="true"></a> <span class="kw">let</span> nine <span class="op">=</span> three <span class="op">*</span> three<span class="op">;</span></span>
111<span id="cb8-4"><a href="#cb8-4"></a> nine * three</span> 111<span id="cb8-4"><a href="#cb8-4" aria-hidden="true"></a> nine <span class="op">*</span> three</span>
112<span id="cb8-5"><a href="#cb8-5"></a><span class="op">}</span>;</span></code></pre></div> 112<span id="cb8-5"><a href="#cb8-5" aria-hidden="true"></a><span class="op">};</span></span></code></pre></div>
113<p>The Go equivalent of the same:</p> 113<p>The Go equivalent of the same:</p>
114<div class="sourceCode" id="cb9"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb9-1"><a href="#cb9-1"></a>twenty_seven := <span class="ot">nil</span></span> 114<div class="sourceCode" id="cb9"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true"></a>twenty_seven := <span class="ot">nil</span></span>
115<span id="cb9-2"><a href="#cb9-2"></a></span> 115<span id="cb9-2"><a href="#cb9-2" aria-hidden="true"></a></span>
116<span id="cb9-3"><a href="#cb9-3"></a>three := <span class="dv">1</span> + <span class="dv">2</span></span> 116<span id="cb9-3"><a href="#cb9-3" aria-hidden="true"></a>three := <span class="dv">1</span> + <span class="dv">2</span></span>
117<span id="cb9-4"><a href="#cb9-4"></a>nine := three * three</span> 117<span id="cb9-4"><a href="#cb9-4" aria-hidden="true"></a>nine := three * three</span>
118<span id="cb9-5"><a href="#cb9-5"></a>twenty_seven = nine * three</span></code></pre></div> 118<span id="cb9-5"><a href="#cb9-5" aria-hidden="true"></a>twenty_seven = nine * three</span></code></pre></div>
119<h3 id="erroring-out-on-unused-variables">Erroring out on unused variables</h3> 119<h3 id="erroring-out-on-unused-variables">Erroring out on unused variables</h3>
120<p>Want to quickly prototype something? Go says no! In all seriousness, a warning would suffice, I don’t want to have to go back and comment each unused import out, only to come back and uncomment them a few seconds later.</p> 120<p>Want to quickly prototype something? Go says no! In all seriousness, a warning would suffice, I don’t want to have to go back and comment each unused import out, only to come back and uncomment them a few seconds later.</p>
121<h3 id="error-handling">Error handling</h3> 121<h3 id="error-handling">Error handling</h3>
122<div class="sourceCode" id="cb10"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb10-1"><a href="#cb10-1"></a><span class="kw">if</span> err != <span class="ot">nil</span> { ... }</span></code></pre></div> 122<div class="sourceCode" id="cb10"><pre class="sourceCode go"><code class="sourceCode go"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true"></a><span class="kw">if</span> err != <span class="ot">nil</span> { ... }</span></code></pre></div>
123<p>Need I say more? I will, for good measure:</p> 123<p>Need I say more? I will, for good measure:</p>
124<ol type="1"> 124<ol type="1">
125<li>Error handling is optional</li> 125<li>Error handling is optional</li>
126<li>Errors are propagated via a clunky <code>if</code> + <code>return</code> statement</li> 126<li>Errors are propagated via a clunky <code>if</code> + <code>return</code> statement</li>
127</ol> 127</ol>
128<p>I prefer Haskell’s “Monadic” error handling, which is employed by Rust as well:</p> 128<p>I prefer Haskell’s “Monadic” error handling, which is employed by Rust as well:</p>
129<div class="sourceCode" id="cb11"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb11-1"><a href="#cb11-1"></a><span class="co">// 1. error handling is compulsory</span></span> 129<div class="sourceCode" id="cb11"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true"></a><span class="co">// 1. error handling is compulsory</span></span>
130<span id="cb11-2"><a href="#cb11-2"></a><span class="co">// 2. errors are propagated with the `?` operator</span></span> 130<span id="cb11-2"><a href="#cb11-2" aria-hidden="true"></a><span class="co">// 2. errors are propagated with the `?` operator</span></span>
131<span id="cb11-3"><a href="#cb11-3"></a><span class="kw">fn</span> foo() -&gt; <span class="dt">Result</span>&lt;<span class="dt">String</span>, <span class="pp">io::</span>Error&gt; <span class="op">{</span></span> 131<span id="cb11-3"><a href="#cb11-3" aria-hidden="true"></a><span class="kw">fn</span> foo() <span class="op">-&gt;</span> <span class="dt">Result</span><span class="op">&lt;</span><span class="dt">String</span><span class="op">,</span> <span class="pp">io::</span><span class="bu">Error</span><span class="op">&gt;</span> <span class="op">{</span></span>
132<span id="cb11-4"><a href="#cb11-4"></a> <span class="kw">let</span> <span class="kw">mut</span> f = <span class="pp">File::</span>open(<span class="st">&quot;foo.txt&quot;</span>)?; <span class="co">// return if error</span></span> 132<span id="cb11-4"><a href="#cb11-4" aria-hidden="true"></a> <span class="kw">let</span> <span class="kw">mut</span> f <span class="op">=</span> <span class="pp">File::</span>open(<span class="st">&quot;foo.txt&quot;</span>)<span class="op">?;</span> <span class="co">// return if error</span></span>
133<span id="cb11-5"><a href="#cb11-5"></a> <span class="kw">let</span> <span class="kw">mut</span> s = <span class="dt">String</span>::new();</span> 133<span id="cb11-5"><a href="#cb11-5" aria-hidden="true"></a> <span class="kw">let</span> <span class="kw">mut</span> s <span class="op">=</span> <span class="dt">String</span><span class="pp">::</span>new()<span class="op">;</span></span>
134<span id="cb11-6"><a href="#cb11-6"></a></span> 134<span id="cb11-6"><a href="#cb11-6" aria-hidden="true"></a></span>
135<span id="cb11-7"><a href="#cb11-7"></a> f.read_to_string(&amp;<span class="kw">mut</span> s)?; <span class="co">// return if error</span></span> 135<span id="cb11-7"><a href="#cb11-7" aria-hidden="true"></a> f<span class="op">.</span>read_to_string(<span class="op">&amp;</span><span class="kw">mut</span> s)<span class="op">?;</span> <span class="co">// return if error</span></span>
136<span id="cb11-8"><a href="#cb11-8"></a></span> 136<span id="cb11-8"><a href="#cb11-8" aria-hidden="true"></a></span>
137<span id="cb11-9"><a href="#cb11-9"></a> <span class="cn">Ok</span>(s) <span class="co">// all good, return a string inside a `Result` context</span></span> 137<span id="cb11-9"><a href="#cb11-9" aria-hidden="true"></a> <span class="cn">Ok</span>(s) <span class="co">// all good, return a string inside a `Result` context</span></span>
138<span id="cb11-10"><a href="#cb11-10"></a><span class="op">}</span></span> 138<span id="cb11-10"><a href="#cb11-10" aria-hidden="true"></a><span class="op">}</span></span>
139<span id="cb11-11"><a href="#cb11-11"></a></span> 139<span id="cb11-11"><a href="#cb11-11" aria-hidden="true"></a></span>
140<span id="cb11-12"><a href="#cb11-12"></a><span class="kw">fn</span> main() <span class="op">{</span></span> 140<span id="cb11-12"><a href="#cb11-12" aria-hidden="true"></a><span class="kw">fn</span> main() <span class="op">{</span></span>
141<span id="cb11-13"><a href="#cb11-13"></a> <span class="co">// `contents` is an enum known as Result:</span></span> 141<span id="cb11-13"><a href="#cb11-13" aria-hidden="true"></a> <span class="co">// `contents` is an enum known as Result:</span></span>
142<span id="cb11-14"><a href="#cb11-14"></a> <span class="kw">let</span> contents = foo();</span> 142<span id="cb11-14"><a href="#cb11-14" aria-hidden="true"></a> <span class="kw">let</span> contents <span class="op">=</span> foo()<span class="op">;</span></span>
143<span id="cb11-15"><a href="#cb11-15"></a> <span class="kw">match</span> contents <span class="op">{</span></span> 143<span id="cb11-15"><a href="#cb11-15" aria-hidden="true"></a> <span class="kw">match</span> contents <span class="op">{</span></span>
144<span id="cb11-16"><a href="#cb11-16"></a> <span class="cn">Ok</span>(c) =&gt; <span class="pp">println!</span>(c),</span> 144<span id="cb11-16"><a href="#cb11-16" aria-hidden="true"></a> <span class="cn">Ok</span>(c) <span class="op">=&gt;</span> <span class="pp">println!</span>(c)<span class="op">,</span></span>
145<span id="cb11-17"><a href="#cb11-17"></a> <span class="cn">Err</span>(e) =&gt; <span class="pp">eprintln!</span>(e)</span> 145<span id="cb11-17"><a href="#cb11-17" aria-hidden="true"></a> <span class="cn">Err</span>(e) <span class="op">=&gt;</span> <span class="pp">eprintln!</span>(e)</span>
146<span id="cb11-18"><a href="#cb11-18"></a> <span class="op">}</span></span> 146<span id="cb11-18"><a href="#cb11-18" aria-hidden="true"></a> <span class="op">}</span></span>
147<span id="cb11-19"><a href="#cb11-19"></a><span class="op">}</span></span></code></pre></div> 147<span id="cb11-19"><a href="#cb11-19" aria-hidden="true"></a><span class="op">}</span></span></code></pre></div>
148<h3 id="conclusion">Conclusion</h3> 148<h3 id="conclusion">Conclusion</h3>
149<p>I did not want to conclude without talking about stylistic choices, lack of metaprogramming, bizzare export rules, but, I am too busy converting my <code>interface{}</code> types into actual generic code for Go v2.</p> 149<p>I did not want to conclude without talking about stylistic choices, lack of metaprogramming, bizzare export rules, but, I am too busy converting my <code>interface{}</code> types into actual generic code for Go v2.</p>
150 150
@@ -159,7 +159,10 @@
159 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 159 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
160 <p> 160 <p>
161 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 161 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
162 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 162 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
163 I also design fonts:
164 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
165 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
163 </p> 166 </p>
164 <p>Send me a mail at [email protected] or a message at [email protected].</p> 167 <p>Send me a mail at [email protected] or a message at [email protected].</p>
165 </div> 168 </div>
diff --git a/docs/posts/hold_position!/index.html b/docs/posts/hold_position!/index.html
index 8948370..24bd92a 100644
--- a/docs/posts/hold_position!/index.html
+++ b/docs/posts/hold_position!/index.html
@@ -58,7 +58,10 @@ winrestview(view) &quot; restore our original view!</code></pre>
58 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 58 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
59 <p> 59 <p>
60 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 60 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
61 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 61 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
62 I also design fonts:
63 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
64 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
62 </p> 65 </p>
63 <p>Send me a mail at [email protected] or a message at [email protected].</p> 66 <p>Send me a mail at [email protected] or a message at [email protected].</p>
64 </div> 67 </div>
diff --git a/docs/posts/my_setup/index.html b/docs/posts/my_setup/index.html
index c24c765..217ba59 100644
--- a/docs/posts/my_setup/index.html
+++ b/docs/posts/my_setup/index.html
@@ -56,7 +56,10 @@
56 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 56 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
57 <p> 57 <p>
58 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 58 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
59 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 59 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
60 I also design fonts:
61 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
62 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
60 </p> 63 </p>
61 <p>Send me a mail at [email protected] or a message at [email protected].</p> 64 <p>Send me a mail at [email protected] or a message at [email protected].</p>
62 </div> 65 </div>
diff --git a/docs/posts/nixOS/index.html b/docs/posts/nixOS/index.html
index de6da96..90de43e 100644
--- a/docs/posts/nixOS/index.html
+++ b/docs/posts/nixOS/index.html
@@ -54,10 +54,10 @@
54<p>Builds may be generated by specifying a <code>default.nix</code> file, and running <code>nix-build</code>. Conventional package managers require you to specify a dependency list, but there is no guarantee that this list is complete. The package will build on your machine even if you forget a dependency. However, with Nix, packages are installed to <code>/nix/store</code>, and not global paths such as <code>/usr/bin/...</code>, if your project builds, it means you have included every last one.</p> 54<p>Builds may be generated by specifying a <code>default.nix</code> file, and running <code>nix-build</code>. Conventional package managers require you to specify a dependency list, but there is no guarantee that this list is complete. The package will build on your machine even if you forget a dependency. However, with Nix, packages are installed to <code>/nix/store</code>, and not global paths such as <code>/usr/bin/...</code>, if your project builds, it means you have included every last one.</p>
55<p>Issues on most my projects have been “unable to build because <code>libxcb</code> is missing”, or “this version of <code>openssl</code> is too old”. Tools like <code>cargo</code> and <code>pip</code> are poor package managers. While they <em>can</em> guarantee that Rust or Python dependencies are met, they make assumptions about the target system.</p> 55<p>Issues on most my projects have been “unable to build because <code>libxcb</code> is missing”, or “this version of <code>openssl</code> is too old”. Tools like <code>cargo</code> and <code>pip</code> are poor package managers. While they <em>can</em> guarantee that Rust or Python dependencies are met, they make assumptions about the target system.</p>
56<p>For example, <a href="https://github.com/nerdypepper/site">this website</a> is now built using Nix, anyone using Nix may simply, clone the repository and run <code>./generate.sh</code>, and it would <em>just work</em>, while keeping your global namespace clean™:</p> 56<p>For example, <a href="https://github.com/nerdypepper/site">this website</a> is now built using Nix, anyone using Nix may simply, clone the repository and run <code>./generate.sh</code>, and it would <em>just work</em>, while keeping your global namespace clean™:</p>
57<div class="sourceCode" id="cb2"><pre class="sourceCode bash"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1"></a><span class="co">#! /usr/bin/env nix-shell</span></span> 57<div class="sourceCode" id="cb2"><pre class="sourceCode bash"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true"></a><span class="co">#! /usr/bin/env nix-shell</span></span>
58<span id="cb2-2"><a href="#cb2-2"></a><span class="co">#! nix-shell -i bash -p eva pandoc esh</span></span> 58<span id="cb2-2"><a href="#cb2-2" aria-hidden="true"></a><span class="co">#! nix-shell -i bash -p eva pandoc esh</span></span>
59<span id="cb2-3"><a href="#cb2-3"></a></span> 59<span id="cb2-3"><a href="#cb2-3" aria-hidden="true"></a></span>
60<span id="cb2-4"><a href="#cb2-4"></a><span class="co"># some bash magic ;)</span></span></code></pre></div> 60<span id="cb2-4"><a href="#cb2-4" aria-hidden="true"></a><span class="co"># some bash magic ;)</span></span></code></pre></div>
61<p>Dependencies are included with the <code>-p</code> flag, the shell script is executed with an interpreter, specified with the <code>-i</code> flag.</p> 61<p>Dependencies are included with the <code>-p</code> flag, the shell script is executed with an interpreter, specified with the <code>-i</code> flag.</p>
62<h3 id="impressions">Impressions</h3> 62<h3 id="impressions">Impressions</h3>
63<p>NixOS is by no means, simple. As a newcomer, using Nix was not easy, heck, I had to learn a purely functional, lazy language to just build programs. There is a lot to be desired on the tooling front as well. A well fleshed out LSP plugin would be nice (<a href="https://github.com/nix-community/rnix-lsp">rnix-lsp looks promising</a>).</p> 63<p>NixOS is by no means, simple. As a newcomer, using Nix was not easy, heck, I had to learn a purely functional, lazy language to just build programs. There is a lot to be desired on the tooling front as well. A well fleshed out LSP plugin would be nice (<a href="https://github.com/nix-community/rnix-lsp">rnix-lsp looks promising</a>).</p>
@@ -76,7 +76,10 @@
76 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 76 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
77 <p> 77 <p>
78 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 78 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
79 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 79 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
80 I also design fonts:
81 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
82 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
80 </p> 83 </p>
81 <p>Send me a mail at [email protected] or a message at [email protected].</p> 84 <p>Send me a mail at [email protected] or a message at [email protected].</p>
82 </div> 85 </div>
diff --git a/docs/posts/onivim_sucks/index.html b/docs/posts/onivim_sucks/index.html
index 1549e3e..0a2a343 100644
--- a/docs/posts/onivim_sucks/index.html
+++ b/docs/posts/onivim_sucks/index.html
@@ -55,7 +55,10 @@
55 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 55 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
56 <p> 56 <p>
57 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 57 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
58 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 58 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
59 I also design fonts:
60 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
61 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
59 </p> 62 </p>
60 <p>Send me a mail at [email protected] or a message at [email protected].</p> 63 <p>Send me a mail at [email protected] or a message at [email protected].</p>
61 </div> 64 </div>
diff --git a/docs/posts/pixel_art_in_GIMP/index.html b/docs/posts/pixel_art_in_GIMP/index.html
index f767de8..7158533 100644
--- a/docs/posts/pixel_art_in_GIMP/index.html
+++ b/docs/posts/pixel_art_in_GIMP/index.html
@@ -47,7 +47,7 @@
47<h3 id="choosing-a-brush">Choosing a Brush</h3> 47<h3 id="choosing-a-brush">Choosing a Brush</h3>
48<p>The most important part of our setup is the brush. Use the Pencil Tool (<code>n</code> on the keyboard) for hard edge drawings. Here’s a small comparison if you don’t know the difference between a hard edge and a soft edge:</p> 48<p>The most important part of our setup is the brush. Use the Pencil Tool (<code>n</code> on the keyboard) for hard edge drawings. Here’s a small comparison if you don’t know the difference between a hard edge and a soft edge:</p>
49<figure> 49<figure>
50<img src="https://u.peppe.rs/kz.png" alt="" /><figcaption>Hard edge vs Soft Edge</figcaption> 50<img src="https://u.peppe.rs/kz.png" alt="Hard edge vs Soft Edge" /><figcaption aria-hidden="true">Hard edge vs Soft Edge</figcaption>
51</figure> 51</figure>
52<p>I turn the size down all the way to 1 (<code>[</code> on the keyboard). Set <code>Dynamics</code> off. <a href="https://u.peppe.rs/Fs.png">Here’s</a> a sample brush configuration.</p> 52<p>I turn the size down all the way to 1 (<code>[</code> on the keyboard). Set <code>Dynamics</code> off. <a href="https://u.peppe.rs/Fs.png">Here’s</a> a sample brush configuration.</p>
53<h3 id="laying-down-the-pixels">Laying down the pixels!</h3> 53<h3 id="laying-down-the-pixels">Laying down the pixels!</h3>
@@ -99,7 +99,10 @@
99 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 99 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
100 <p> 100 <p>
101 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 101 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
102 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 102 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
103 I also design fonts:
104 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
105 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
103 </p> 106 </p>
104 <p>Send me a mail at [email protected] or a message at [email protected].</p> 107 <p>Send me a mail at [email protected] or a message at [email protected].</p>
105 </div> 108 </div>
diff --git a/docs/posts/rapid_refactoring_with_vim/index.html b/docs/posts/rapid_refactoring_with_vim/index.html
index d8a1c25..ff6cb4c 100644
--- a/docs/posts/rapid_refactoring_with_vim/index.html
+++ b/docs/posts/rapid_refactoring_with_vim/index.html
@@ -40,34 +40,34 @@
40 <div class="post-text"> 40 <div class="post-text">
41 <p>Last weekend, I was tasked with refactoring the 96 unit tests on <a href="https://github.com/ruma/ruma-events/pull/70">ruma-events</a> to use strictly typed json objects using <code>serde_json::json!</code> instead of raw strings. It was rather painless thanks to vim :)</p> 41 <p>Last weekend, I was tasked with refactoring the 96 unit tests on <a href="https://github.com/ruma/ruma-events/pull/70">ruma-events</a> to use strictly typed json objects using <code>serde_json::json!</code> instead of raw strings. It was rather painless thanks to vim :)</p>
42<p>Here’s a small sample of what had to be done (note the lines prefixed with the arrow):</p> 42<p>Here’s a small sample of what had to be done (note the lines prefixed with the arrow):</p>
43<div class="sourceCode" id="cb1"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb1-1"><a href="#cb1-1"></a>→ <span class="kw">use</span> <span class="pp">serde_json::</span><span class="op">{</span>from_str<span class="op">}</span>;</span> 43<div class="sourceCode" id="cb1"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true"></a>→ <span class="kw">use</span> <span class="pp">serde_json::</span><span class="op">{</span>from_str<span class="op">};</span></span>
44<span id="cb1-2"><a href="#cb1-2"></a> </span> 44<span id="cb1-2"><a href="#cb1-2" aria-hidden="true"></a> </span>
45<span id="cb1-3"><a href="#cb1-3"></a> <span class="at">#[</span>test<span class="at">]</span></span> 45<span id="cb1-3"><a href="#cb1-3" aria-hidden="true"></a> <span class="at">#[</span>test<span class="at">]</span></span>
46<span id="cb1-4"><a href="#cb1-4"></a> <span class="kw">fn</span> deserialize() <span class="op">{</span></span> 46<span id="cb1-4"><a href="#cb1-4" aria-hidden="true"></a> <span class="kw">fn</span> deserialize() <span class="op">{</span></span>
47<span id="cb1-5"><a href="#cb1-5"></a> <span class="pp">assert_eq!</span>(</span> 47<span id="cb1-5"><a href="#cb1-5" aria-hidden="true"></a> <span class="pp">assert_eq!</span>(</span>
48<span id="cb1-6"><a href="#cb1-6"></a>→ <span class="pp">from_str::</span>&lt;Action&gt;(<span class="st">r#&quot;{&quot;set_tweak&quot;: &quot;highlight&quot;}&quot;#</span>),</span> 48<span id="cb1-6"><a href="#cb1-6" aria-hidden="true"></a>→ <span class="pp">from_str::</span><span class="op">&lt;</span>Action<span class="op">&gt;</span>(<span class="st">r#&quot;{&quot;set_tweak&quot;: &quot;highlight&quot;}&quot;#</span>)<span class="op">,</span></span>
49<span id="cb1-7"><a href="#cb1-7"></a> <span class="pp">Action::</span>SetTweak(<span class="pp">Tweak::</span>Highlight <span class="op">{</span> value: <span class="cn">true</span> <span class="op">}</span>)</span> 49<span id="cb1-7"><a href="#cb1-7" aria-hidden="true"></a> <span class="pp">Action::</span>SetTweak(<span class="pp">Tweak::</span>Highlight <span class="op">{</span> value<span class="op">:</span> <span class="cn">true</span> <span class="op">}</span>)</span>
50<span id="cb1-8"><a href="#cb1-8"></a> );</span> 50<span id="cb1-8"><a href="#cb1-8" aria-hidden="true"></a> )<span class="op">;</span></span>
51<span id="cb1-9"><a href="#cb1-9"></a> <span class="op">}</span></span></code></pre></div> 51<span id="cb1-9"><a href="#cb1-9" aria-hidden="true"></a> <span class="op">}</span></span></code></pre></div>
52<p>had to be converted to:</p> 52<p>had to be converted to:</p>
53<div class="sourceCode" id="cb2"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb2-1"><a href="#cb2-1"></a>→ <span class="kw">use</span> <span class="pp">serde_json::</span><span class="op">{</span>from_value<span class="op">}</span>;</span> 53<div class="sourceCode" id="cb2"><pre class="sourceCode rust"><code class="sourceCode rust"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true"></a>→ <span class="kw">use</span> <span class="pp">serde_json::</span><span class="op">{</span>from_value<span class="op">};</span></span>
54<span id="cb2-2"><a href="#cb2-2"></a> </span> 54<span id="cb2-2"><a href="#cb2-2" aria-hidden="true"></a> </span>
55<span id="cb2-3"><a href="#cb2-3"></a> <span class="at">#[</span>test<span class="at">]</span></span> 55<span id="cb2-3"><a href="#cb2-3" aria-hidden="true"></a> <span class="at">#[</span>test<span class="at">]</span></span>
56<span id="cb2-4"><a href="#cb2-4"></a> <span class="kw">fn</span> deserialize() <span class="op">{</span></span> 56<span id="cb2-4"><a href="#cb2-4" aria-hidden="true"></a> <span class="kw">fn</span> deserialize() <span class="op">{</span></span>
57<span id="cb2-5"><a href="#cb2-5"></a> <span class="pp">assert_eq!</span>(</span> 57<span id="cb2-5"><a href="#cb2-5" aria-hidden="true"></a> <span class="pp">assert_eq!</span>(</span>
58<span id="cb2-6"><a href="#cb2-6"></a>→ <span class="pp">from_value::</span>&lt;Action&gt;(<span class="pp">json!</span>(<span class="op">{</span><span class="st">&quot;set_tweak&quot;</span>: <span class="st">&quot;highlight&quot;</span><span class="op">}</span>)),</span> 58<span id="cb2-6"><a href="#cb2-6" aria-hidden="true"></a>→ <span class="pp">from_value::</span><span class="op">&lt;</span>Action<span class="op">&gt;</span>(<span class="pp">json!</span>(<span class="op">{</span><span class="st">&quot;set_tweak&quot;</span><span class="op">:</span> <span class="st">&quot;highlight&quot;</span><span class="op">}</span>))<span class="op">,</span></span>
59<span id="cb2-7"><a href="#cb2-7"></a> <span class="pp">Action::</span>SetTweak(<span class="pp">Tweak::</span>Highlight <span class="op">{</span> value: <span class="cn">true</span> <span class="op">}</span>)</span> 59<span id="cb2-7"><a href="#cb2-7" aria-hidden="true"></a> <span class="pp">Action::</span>SetTweak(<span class="pp">Tweak::</span>Highlight <span class="op">{</span> value<span class="op">:</span> <span class="cn">true</span> <span class="op">}</span>)</span>
60<span id="cb2-8"><a href="#cb2-8"></a> );</span> 60<span id="cb2-8"><a href="#cb2-8" aria-hidden="true"></a> )<span class="op">;</span></span>
61<span id="cb2-9"><a href="#cb2-9"></a> <span class="op">}</span></span></code></pre></div> 61<span id="cb2-9"><a href="#cb2-9" aria-hidden="true"></a> <span class="op">}</span></span></code></pre></div>
62<h3 id="the-arglist">The arglist</h3> 62<h3 id="the-arglist">The arglist</h3>
63<p>For the initial pass, I decided to handle imports, this was a simple find and replace operation, done to all the files containing tests. Luckily, modules (and therefore files) containing tests in Rust are annotated with the <code>#[cfg(test)]</code> attribute. I opened all such files:</p> 63<p>For the initial pass, I decided to handle imports, this was a simple find and replace operation, done to all the files containing tests. Luckily, modules (and therefore files) containing tests in Rust are annotated with the <code>#[cfg(test)]</code> attribute. I opened all such files:</p>
64<div class="sourceCode" id="cb3"><pre class="sourceCode bash"><code class="sourceCode bash"><span id="cb3-1"><a href="#cb3-1"></a><span class="co"># `grep -l pattern files` lists all the files</span></span> 64<div class="sourceCode" id="cb3"><pre class="sourceCode bash"><code class="sourceCode bash"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true"></a><span class="co"># `grep -l pattern files` lists all the files</span></span>
65<span id="cb3-2"><a href="#cb3-2"></a><span class="co"># matching the pattern</span></span> 65<span id="cb3-2"><a href="#cb3-2" aria-hidden="true"></a><span class="co"># matching the pattern</span></span>
66<span id="cb3-3"><a href="#cb3-3"></a></span> 66<span id="cb3-3"><a href="#cb3-3" aria-hidden="true"></a></span>
67<span id="cb3-4"><a href="#cb3-4"></a><span class="ex">vim</span> <span class="va">$(</span><span class="fu">grep</span> -l <span class="st">&#39;cfg\(test\)&#39;</span> ./**/*.rs<span class="va">)</span></span> 67<span id="cb3-4"><a href="#cb3-4" aria-hidden="true"></a><span class="ex">vim</span> <span class="va">$(</span><span class="fu">grep</span> -l <span class="st">&#39;cfg\(test\)&#39;</span> ./**/*.rs<span class="va">)</span></span>
68<span id="cb3-5"><a href="#cb3-5"></a></span> 68<span id="cb3-5"><a href="#cb3-5" aria-hidden="true"></a></span>
69<span id="cb3-6"><a href="#cb3-6"></a><span class="co"># expands to something like:</span></span> 69<span id="cb3-6"><a href="#cb3-6" aria-hidden="true"></a><span class="co"># expands to something like:</span></span>
70<span id="cb3-7"><a href="#cb3-7"></a><span class="ex">vim</span> push_rules.rs room/member.rs key/verification/lib.rs</span></code></pre></div> 70<span id="cb3-7"><a href="#cb3-7" aria-hidden="true"></a><span class="ex">vim</span> push_rules.rs room/member.rs key/verification/lib.rs</span></code></pre></div>
71<p>Starting vim with more than one file at the shell prompt populates the arglist. Hit <code>:args</code> to see the list of files currently ready to edit. The square [brackets] indicate the current file. Navigate through the arglist with <code>:next</code> and <code>:prev</code>. I use tpope’s vim-unimpaired <a href="#fn1" class="footnote-ref" id="fnref1" role="doc-noteref"><sup>1</sup></a>, which adds <code>]a</code> and <code>[a</code>, mapped to <code>:next</code> and <code>:prev</code>.</p> 71<p>Starting vim with more than one file at the shell prompt populates the arglist. Hit <code>:args</code> to see the list of files currently ready to edit. The square [brackets] indicate the current file. Navigate through the arglist with <code>:next</code> and <code>:prev</code>. I use tpope’s vim-unimpaired <a href="#fn1" class="footnote-ref" id="fnref1" role="doc-noteref"><sup>1</sup></a>, which adds <code>]a</code> and <code>[a</code>, mapped to <code>:next</code> and <code>:prev</code>.</p>
72<p>All that’s left to do is the find and replace, for which we will be using vim’s <code>argdo</code>, applying a substitution to every file in the arglist:</p> 72<p>All that’s left to do is the find and replace, for which we will be using vim’s <code>argdo</code>, applying a substitution to every file in the arglist:</p>
73<pre><code>:argdo s/from_str/from_value/g</code></pre> 73<pre><code>:argdo s/from_str/from_value/g</code></pre>
@@ -139,7 +139,10 @@ BUFFER: json!( ... );</code></pre>
139 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 139 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
140 <p> 140 <p>
141 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 141 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
142 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 142 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
143 I also design fonts:
144 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
145 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
143 </p> 146 </p>
144 <p>Send me a mail at [email protected] or a message at [email protected].</p> 147 <p>Send me a mail at [email protected] or a message at [email protected].</p>
145 </div> 148 </div>
diff --git a/docs/posts/self-hosting_git/index.html b/docs/posts/self-hosting_git/index.html
new file mode 100644
index 0000000..67ef514
--- /dev/null
+++ b/docs/posts/self-hosting_git/index.html
@@ -0,0 +1,189 @@
1<!DOCTYPE html>
2<html lang="en">
3 <head>
4 <link rel="stylesheet" href="/style.css">
5 <link rel="stylesheet" href="/syntax.css">
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15 <title>Self-hosting Git · peppe.rs</title>
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17 <div class="posts">
18 <div class="post">
19 <a href="/" class="post-end-link">⟵ Back</a>
20 <a class="stats post-end-link" href="https://raw.githubusercontent.com/nerdypepper/site/master/posts/self-hosting_git.md
21">View Raw</a>
22 <div class="separator"></div>
23 <div class="date">
24 17/10 — 2020
25 <div class="stats">
26 <span class="stats-number">
27 87.90
28 </span>
29 <span class="stats-unit">cm</span>
30 &nbsp
31 <span class="stats-number">
32 5.4
33 </span>
34 <span class="stats-unit">min</span>
35 </div>
36 </div>
37 <h1>
38 Self-hosting Git
39 </h1>
40 <div class="post-text">
41 <p>Earlier this week, I began migrating my repositories from Github to <a href="https://git.zx2c4.com/">cgit</a>. If you care at all about big corporates turning open-source into a T-shirt farming service, this is the way to go.</p>
42<h3 id="offerings">Offerings</h3>
43<p>cgit is <em>very</em> bare bones. It is <a href="https://tools.ietf.org/html/rfc3875">cgi</a> web interface interface to git, and nothing more. You may browse repositories, view diffs, commit logs and even clone via http. If you are looking to replace Github with cgit, keep in mind that cgit does not handle issues or pull/merge requests. If people wish to contribute to your work, they would have to send you a patch via email.</p>
44<h3 id="setup">Setup</h3>
45<p>Installing cgit is fairly straightforward, if you would like to compile it from source:</p>
46<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true"></a><span class="co"># fetch</span></span>
47<span id="cb1-2"><a href="#cb1-2" aria-hidden="true"></a><span class="fu">git</span> clone https://git.zx2c4.com <span class="kw">&amp;&amp;</span> <span class="bu">cd</span> cgit</span>
48<span id="cb1-3"><a href="#cb1-3" aria-hidden="true"></a><span class="fu">git</span> submodule init</span>
49<span id="cb1-4"><a href="#cb1-4" aria-hidden="true"></a><span class="fu">git</span> submodule update</span>
50<span id="cb1-5"><a href="#cb1-5" aria-hidden="true"></a></span>
51<span id="cb1-6"><a href="#cb1-6" aria-hidden="true"></a><span class="co"># install</span></span>
52<span id="cb1-7"><a href="#cb1-7" aria-hidden="true"></a><span class="fu">make</span> NO_LUA=1</span>
53<span id="cb1-8"><a href="#cb1-8" aria-hidden="true"></a><span class="fu">sudo</span> make install</span></code></pre></div>
54<p>This would drop the cgit cgi script (and the default css) into <code>/var/www/htdocs/cgit</code>. You may configure cgit by editing <code>/etc/cgitrc</code>. I specify the <code>NO_LUA</code> flag to compile without lua support, exclude that flag if you would like to extend cgit via lua scripts.</p>
55<h3 id="going-live">Going live</h3>
56<p>You might want to use, <a href="https://github.com/gnosek/fcgiwrap">fcgiwrap</a>, a <a href="http://www.nongnu.org/fastcgi">fastcgi</a> wrapper for <code>cgi</code> scripts,</p>
57<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true"></a><span class="fu">sudo</span> apt install fcgiwrap</span>
58<span id="cb2-2"><a href="#cb2-2" aria-hidden="true"></a><span class="fu">sudo</span> systemctl start fcgiwrap.socket</span></code></pre></div>
59<p>Expose the cgit cgi script to the web via <code>nginx</code>:</p>
60<pre><code># nginx.conf
61server {
62 listen 80;
63 server_name git.example.com;
64
65 # serve static files
66 location ~* ^.+\.(css|png|ico)$ {
67 root /var/www/htdocs/cgit;
68 }
69
70 location / {
71 fastcgi_pass unix:/run/fcgiwrap.socket;
72 fastcgi_param SCRIPT_FILENAME /var/www/htdocs/cgit/cgit.cgi; # the default location of the cgit cgi script
73 fastcgi_param PATH_INFO $uri;
74 fastcgi_param QUERY_STRING $args;
75 }
76}</code></pre>
77<p>Point cgit to your git repositories:</p>
78<pre><code># /etc/cgitrc
79scan-path=/path/to/git/repos</code></pre>
80<p><strong><em>Note</em></strong>: <em><code>scan-path</code> works best if you stick it at the end of your <code>cgitrc</code></em>.</p>
81<p>You may now create remote repositories at <code>/path/to/git/repos</code>, via:</p>
82<pre><code>git init --bare</code></pre>
83<p>Add the remote to your local repository:</p>
84<pre><code>git remote set-url origin user@remote:/above/path
85git push origin master</code></pre>
86<h3 id="configuration">Configuration</h3>
87<p>cgit is fairly easy to configure, all configuration options can be found <a href="https://git.zx2c4.com/cgit/tree/cgitrc.5.txt">in the manual</a>, here are a couple of cool ones though:</p>
88<p><strong>enable-commit-graph</strong>: Generates a text based graphical representation of the commit history, similar to <code>git log --graph --oneline</code>.</p>
89<pre><code>| * | Add support for configuration file
90* | | simplify command parsing logic
91* | | Refactor parsers
92* | | Add basic tests
93* | | Merge remote-tracking branch &#39;origin/master&#39; in...
94|\| |
95| * | add installation instructions for nix
96| * | switch to pancurses backendv0.2.2
97| * | bump to v0.2.2
98* | | Merge branch &#39;master&#39; into feature/larger-names...
99|\| |
100| * | enable feature based compilation to support win...
101| * | remove dependency on rustc v1.45, bump to v0.2....
102| * | Merge branch &#39;feature/windows&#39; of https://git...
103| |\ \
104| | * | add windows to github actions
105| | * | switch to crossterm backend
106| | * | Merge branch &#39;fix/duplicate-habits&#39;
107| | |\ \
108| | | * | move duplicate check to command parsing blo...</code></pre>
109<p><strong>section-from-path</strong>: This option paired with <code>scan-path</code> will automatically generate sections in your cgit index page, from the path to each repo. For example, the directory structure used to generate sections on <a href="https://git.peppe.rs">my cgit instance</a> looks like this:</p>
110<pre><code>├── cli
111│ ├── dijo
112│ ├── eva
113│ ├── pista
114│ ├── taizen
115│ └── xcursorlocate
116├── config
117│ ├── dotfiles
118│ └── nixos
119├── fonts
120│ ├── curie
121│ └── scientifica
122├── languages
123│ └── lisk
124├── libs
125│ ├── cutlass
126│ └── fondant
127├── terminfo
128├── university
129│ └── furby
130└── web
131 └── isostatic</code></pre>
132<h3 id="ease-of-use">Ease of use</h3>
133<p>As I mentioned before, <code>cgit</code> is simply a view into your git repositories, you will have to manually create new repositories by entering your remote and using <code>git init --bare</code>. Here are a couple of scripts I wrote to perform actions on remotes, think of it as a smaller version of Github’s <code>gh</code> program.</p>
134<p>You may save these scripts as <code>git-script-name</code> and drop them in your <code>$PATH</code>, and git will automatically add an alias called <code>script-name</code>, callable via:</p>
135<pre><code>git script-name</code></pre>
136<h4 id="git-new-repo">git-new-repo</h4>
137<p>Creates a new repository on your remote, the first arg may be a path (section/repo-name) or just the repo name:</p>
138<pre><code>#! /usr/bin/env bash
139#
140# usage:
141# git new-repo section/repo-name
142#
143# example:
144# git new-repo fonts/scientifica
145# creates: user@remote:fonts/scientifica
146
147if [ $# -eq 0 ]; then
148 echo &quot;requires an arg&quot;
149 exit 1
150fi
151
152ssh user@remote git init --bare &quot;$1&quot;;</code></pre>
153<h4 id="git-set-desc">git-set-desc</h4>
154<p>To set a one line repository description. It simply copies the local <code>.git/description</code>, into <code>remote/description</code>. <code>cgit</code> displays the contents of this file on the index page:</p>
155<pre><code>#! /usr/bin/env bash
156#
157# usage:
158# enter repo description into .git/description and run:
159# git set-desc
160
161remote=$(git remote get-url --push origin)
162scp .git/description &quot;$remote/description&quot;</code></pre>
163
164 </div>
165
166 <div class=intro>
167 Hi.
168 <div class=hot-links>
169 <a href=https://peppe.rs/index.xml class=feed-button>Subscribe</a>
170 <a href=https://liberapay.com/nerdypepper/donate class=donate-button>Donate</a>
171 </div>
172 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
173 <p>
174 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
175 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
176 I also design fonts:
177 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
178 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
179 </p>
180 <p>Send me a mail at [email protected] or a message at [email protected].</p>
181 </div>
182
183 <a href="/" class="post-end-link">⟵ Back</a>
184 <a class="stats post-end-link" href="https://raw.githubusercontent.com/nerdypepper/site/master/posts/self-hosting_git.md
185">View Raw</a>
186 </div>
187 </div>
188 </body>
189</html>
diff --git a/docs/posts/static_sites_with_bash/index.html b/docs/posts/static_sites_with_bash/index.html
index 86e4a12..67f5d8b 100644
--- a/docs/posts/static_sites_with_bash/index.html
+++ b/docs/posts/static_sites_with_bash/index.html
@@ -43,26 +43,26 @@
43<p>I chose to write in markdown, and convert to html with <a href="https://kristaps.bsd.lv/lowdown/">lowdown</a>.</p> 43<p>I chose to write in markdown, and convert to html with <a href="https://kristaps.bsd.lv/lowdown/">lowdown</a>.</p>
44<h3 id="directory-structure">Directory structure</h3> 44<h3 id="directory-structure">Directory structure</h3>
45<p>I host my site on GitHub pages, so <code>docs/</code> has to be the entry point. Markdown formatted posts go into <code>posts/</code>, get converted into html, and end up in <code>docs/index.html</code>, something like this:</p> 45<p>I host my site on GitHub pages, so <code>docs/</code> has to be the entry point. Markdown formatted posts go into <code>posts/</code>, get converted into html, and end up in <code>docs/index.html</code>, something like this:</p>
46<div class="sourceCode" id="cb1"><pre class="sourceCode bash"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1"></a><span class="va">posts=$(</span><span class="fu">ls</span> -t ./posts<span class="va">)</span> <span class="co"># chronological order!</span></span> 46<div class="sourceCode" id="cb1"><pre class="sourceCode bash"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true"></a><span class="va">posts=$(</span><span class="fu">ls</span> -t ./posts<span class="va">)</span> # <span class="ex">chronological</span> order!</span>
47<span id="cb1-2"><a href="#cb1-2"></a><span class="kw">for</span> <span class="ex">f</span> in <span class="va">$posts</span><span class="kw">;</span> <span class="kw">do</span></span> 47<span id="cb1-2"><a href="#cb1-2" aria-hidden="true"></a><span class="kw">for</span> <span class="ex">f</span> in <span class="va">$posts</span><span class="kw">;</span> <span class="kw">do</span></span>
48<span id="cb1-3"><a href="#cb1-3"></a> <span class="va">file=</span><span class="st">&quot;./posts/&quot;</span><span class="va">$f</span> <span class="co"># `ls` mangled our file paths</span></span> 48<span id="cb1-3"><a href="#cb1-3" aria-hidden="true"></a> <span class="va">file=</span><span class="st">&quot;./posts/&quot;</span><span class="va">$f</span> # <span class="kw">`</span><span class="fu">ls</span><span class="kw">`</span> <span class="ex">mangled</span> our file paths</span>
49<span id="cb1-4"><a href="#cb1-4"></a> <span class="bu">echo</span> <span class="st">&quot;generating post </span><span class="va">$file</span><span class="st">&quot;</span></span> 49<span id="cb1-4"><a href="#cb1-4" aria-hidden="true"></a> <span class="bu">echo</span> <span class="st">&quot;generating post </span><span class="va">$file</span><span class="st">&quot;</span></span>
50<span id="cb1-5"><a href="#cb1-5"></a></span> 50<span id="cb1-5"><a href="#cb1-5" aria-hidden="true"></a></span>
51<span id="cb1-6"><a href="#cb1-6"></a> <span class="va">html=$(</span><span class="ex">lowdown</span> <span class="st">&quot;</span><span class="va">$file</span><span class="st">&quot;</span><span class="va">)</span></span> 51<span id="cb1-6"><a href="#cb1-6" aria-hidden="true"></a> <span class="va">html=$(</span><span class="ex">lowdown</span> <span class="st">&quot;</span><span class="va">$file</span><span class="st">&quot;</span><span class="va">)</span></span>
52<span id="cb1-7"><a href="#cb1-7"></a> <span class="bu">echo</span> -e <span class="st">&quot;html&quot;</span> <span class="op">&gt;&gt;</span> docs/index.html</span> 52<span id="cb1-7"><a href="#cb1-7" aria-hidden="true"></a> <span class="bu">echo</span> -e <span class="st">&quot;html&quot;</span> <span class="op">&gt;&gt;</span> docs/index.html</span>
53<span id="cb1-8"><a href="#cb1-8"></a><span class="kw">done</span></span></code></pre></div> 53<span id="cb1-8"><a href="#cb1-8" aria-hidden="true"></a><span class="kw">done</span></span></code></pre></div>
54<h3 id="assets">Assets</h3> 54<h3 id="assets">Assets</h3>
55<p>Most static site generators recommend dropping image assets into the site source itself. That does have it’s merits, but I prefer hosting images separately:</p> 55<p>Most static site generators recommend dropping image assets into the site source itself. That does have it’s merits, but I prefer hosting images separately:</p>
56<div class="sourceCode" id="cb2"><pre class="sourceCode bash"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1"></a><span class="co"># strip file extension</span></span> 56<div class="sourceCode" id="cb2"><pre class="sourceCode bash"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true"></a><span class="co"># strip file extension</span></span>
57<span id="cb2-2"><a href="#cb2-2"></a><span class="va">ext=</span><span class="st">&quot;</span><span class="va">${1##</span>*.<span class="va">}</span><span class="st">&quot;</span></span> 57<span id="cb2-2"><a href="#cb2-2" aria-hidden="true"></a><span class="va">ext=</span><span class="st">&quot;</span><span class="va">${1##</span>*.<span class="va">}</span><span class="st">&quot;</span></span>
58<span id="cb2-3"><a href="#cb2-3"></a></span> 58<span id="cb2-3"><a href="#cb2-3" aria-hidden="true"></a></span>
59<span id="cb2-4"><a href="#cb2-4"></a><span class="co"># generate a random file name</span></span> 59<span id="cb2-4"><a href="#cb2-4" aria-hidden="true"></a><span class="co"># generate a random file name</span></span>
60<span id="cb2-5"><a href="#cb2-5"></a><span class="va">id=$(</span> <span class="fu">cat</span> /dev/urandom <span class="kw">|</span> <span class="fu">tr</span> -dc <span class="st">&#39;a-zA-Z0-9&#39;</span> <span class="kw">|</span> <span class="ex">fold</span> -w 2 <span class="kw">|</span> <span class="fu">head</span> -n 1 <span class="va">)</span></span> 60<span id="cb2-5"><a href="#cb2-5" aria-hidden="true"></a><span class="va">id=$(</span> <span class="fu">cat</span> /dev/urandom <span class="kw">|</span> <span class="fu">tr</span> -dc <span class="st">&#39;a-zA-Z0-9&#39;</span> <span class="kw">|</span> <span class="ex">fold</span> -w 2 <span class="kw">|</span> <span class="fu">head</span> -n 1 <span class="va">)</span></span>
61<span id="cb2-6"><a href="#cb2-6"></a><span class="va">id=</span><span class="st">&quot;</span><span class="va">$id</span><span class="st">.</span><span class="va">$ext</span><span class="st">&quot;</span></span> 61<span id="cb2-6"><a href="#cb2-6" aria-hidden="true"></a><span class="va">id=</span><span class="st">&quot;</span><span class="va">$id</span><span class="st">.</span><span class="va">$ext</span><span class="st">&quot;</span></span>
62<span id="cb2-7"><a href="#cb2-7"></a></span> 62<span id="cb2-7"><a href="#cb2-7" aria-hidden="true"></a></span>
63<span id="cb2-8"><a href="#cb2-8"></a><span class="co"># copy to my file host</span></span> 63<span id="cb2-8"><a href="#cb2-8" aria-hidden="true"></a><span class="co"># copy to my file host</span></span>
64<span id="cb2-9"><a href="#cb2-9"></a><span class="fu">scp</span> -P 443 <span class="st">&quot;</span><span class="va">$1</span><span class="st">&quot;</span> emerald:files/<span class="st">&quot;</span><span class="va">$id</span><span class="st">&quot;</span> </span> 64<span id="cb2-9"><a href="#cb2-9" aria-hidden="true"></a><span class="fu">scp</span> -P 443 <span class="st">&quot;</span><span class="va">$1</span><span class="st">&quot;</span> emerald:files/<span class="st">&quot;</span><span class="va">$id</span><span class="st">&quot;</span> </span>
65<span id="cb2-10"><a href="#cb2-10"></a><span class="bu">echo</span> <span class="st">&quot;https://u.peppe.rs/</span><span class="va">$id</span><span class="st">&quot;</span></span></code></pre></div> 65<span id="cb2-10"><a href="#cb2-10" aria-hidden="true"></a><span class="bu">echo</span> <span class="st">&quot;https://u.peppe.rs/</span><span class="va">$id</span><span class="st">&quot;</span></span></code></pre></div>
66<h3 id="templating">Templating</h3> 66<h3 id="templating">Templating</h3>
67<p><a href="https://github.com/NerdyPepper/site/blob/master/generate.sh"><code>generate.sh</code></a> brings the above bits and pieces together (with some extra cruft to avoid javascript). It uses <code>sed</code> to produce nice titles from the file names (removes underscores, title-case), and <code>date(1)</code> to add the date to each post listing!</p> 67<p><a href="https://github.com/NerdyPepper/site/blob/master/generate.sh"><code>generate.sh</code></a> brings the above bits and pieces together (with some extra cruft to avoid javascript). It uses <code>sed</code> to produce nice titles from the file names (removes underscores, title-case), and <code>date(1)</code> to add the date to each post listing!</p>
68 68
@@ -77,7 +77,10 @@
77 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 77 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
78 <p> 78 <p>
79 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 79 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
80 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 80 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
81 I also design fonts:
82 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
83 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
81 </p> 84 </p>
82 <p>Send me a mail at [email protected] or a message at [email protected].</p> 85 <p>Send me a mail at [email protected] or a message at [email protected].</p>
83 </div> 86 </div>
diff --git a/docs/posts/termux_tandem/index.html b/docs/posts/termux_tandem/index.html
index 37088bb..d5df2ea 100644
--- a/docs/posts/termux_tandem/index.html
+++ b/docs/posts/termux_tandem/index.html
@@ -68,7 +68,10 @@ mtZabXG.jpg p8d5c584f2841.jpg vjUxGjq.jpg</code></pre>
68 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 68 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
69 <p> 69 <p>
70 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 70 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
71 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 71 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
72 I also design fonts:
73 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
74 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
72 </p> 75 </p>
73 <p>Send me a mail at [email protected] or a message at [email protected].</p> 76 <p>Send me a mail at [email protected] or a message at [email protected].</p>
74 </div> 77 </div>
diff --git a/docs/posts/turing_complete_type_systems/index.html b/docs/posts/turing_complete_type_systems/index.html
index cc51210..0d3ea6c 100644
--- a/docs/posts/turing_complete_type_systems/index.html
+++ b/docs/posts/turing_complete_type_systems/index.html
@@ -59,7 +59,10 @@
59 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 59 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
60 <p> 60 <p>
61 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 61 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
62 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 62 I write <a href=https://git.peppe.rs>open-source stuff</a> to pass time.
63 I also design fonts:
64 <a href=https://git.peppe.rs/fonts/scientifica>scientifica</a>,
65 <a href=https://git.peppe.rs/fonts/curie>curie</a>.
63 </p> 66 </p>
64 <p>Send me a mail at [email protected] or a message at [email protected].</p> 67 <p>Send me a mail at [email protected] or a message at [email protected].</p>
65 </div> 68 </div>
diff --git a/generate.sh b/generate.sh
index 0495d42..b246d61 100755
--- a/generate.sh
+++ b/generate.sh
@@ -53,7 +53,10 @@ intro() {
53 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p> 53 <p>I'm Akshay, I go by nerd or nerdypepper on the internet.</p>
54 <p> 54 <p>
55 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer. 55 I am a compsci undergrad, Rust programmer and an enthusiastic Vimmer.
56 I write open-source stuff to pass time. I also design fonts: scientifica, curie. 56 I write <a href="https://git.peppe.rs">open-source stuff</a> to pass time.
57 I also design fonts:
58 <a href="https://git.peppe.rs/fonts/scientifica">scientifica</a>,
59 <a href="https://git.peppe.rs/fonts/curie">curie</a>.
57 </p> 60 </p>
58 <p>Send me a mail at [email protected] or a message at [email protected].</p> 61 <p>Send me a mail at [email protected] or a message at [email protected].</p>
59 </div> 62 </div>
diff --git a/posts/self-hosting_git.md b/posts/self-hosting_git.md
new file mode 100644
index 0000000..6d0e1a4
--- /dev/null
+++ b/posts/self-hosting_git.md
@@ -0,0 +1,220 @@
1Earlier this week, I began migrating my repositories from
2Github to [cgit](https://git.zx2c4.com/). If you care at
3all about big corporates turning open-source into a T-shirt
4farming service, this is the way to go.
5
6### Offerings
7
8cgit is *very* bare bones. It is
9[cgi](https://tools.ietf.org/html/rfc3875) web interface
10interface to git, and nothing more. You may browse
11repositories, view diffs, commit logs and even clone via
12http. If you are looking to replace Github with cgit, keep
13in mind that cgit does not handle issues or pull/merge
14requests. If people wish to contribute to your work, they
15would have to send you a patch via email.
16
17### Setup
18
19Installing cgit is fairly straightforward, if you would
20like to compile it from source:
21
22```sh
23# fetch
24git clone https://git.zx2c4.com && cd cgit
25git submodule init
26git submodule update
27
28# install
29make NO_LUA=1
30sudo make install
31```
32
33This would drop the cgit cgi script (and the default css)
34into `/var/www/htdocs/cgit`. You may configure cgit by
35editing `/etc/cgitrc`. I specify the `NO_LUA` flag to
36compile without lua support, exclude that flag if you would
37like to extend cgit via lua scripts.
38
39### Going live
40
41You might want to use,
42[fcgiwrap](https://github.com/gnosek/fcgiwrap), a
43[fastcgi](http://www.nongnu.org/fastcgi) wrapper for `cgi`
44scripts,
45
46```sh
47sudo apt install fcgiwrap
48sudo systemctl start fcgiwrap.socket
49```
50
51Expose the cgit cgi script to the web via `nginx`:
52
53```
54# nginx.conf
55server {
56 listen 80;
57 server_name git.example.com;
58
59 # serve static files
60 location ~* ^.+\.(css|png|ico)$ {
61 root /var/www/htdocs/cgit;
62 }
63
64 location / {
65 fastcgi_pass unix:/run/fcgiwrap.socket;
66 fastcgi_param SCRIPT_FILENAME /var/www/htdocs/cgit/cgit.cgi; # the default location of the cgit cgi script
67 fastcgi_param PATH_INFO $uri;
68 fastcgi_param QUERY_STRING $args;
69 }
70}
71```
72
73Point cgit to your git repositories:
74
75```
76# /etc/cgitrc
77scan-path=/path/to/git/repos
78```
79
80***Note***: *`scan-path` works best if you stick it at the end of your
81`cgitrc`*.
82
83You may now create remote repositories at
84`/path/to/git/repos`, via:
85
86```
87git init --bare
88```
89
90Add the remote to your local repository:
91
92```
93git remote set-url origin user@remote:/above/path
94git push origin master
95```
96
97### Configuration
98
99cgit is fairly easy to configure, all configuration
100options can be found [in the
101manual](https://git.zx2c4.com/cgit/tree/cgitrc.5.txt), here
102are a couple of cool ones though:
103
104**enable-commit-graph**: Generates a text based graphical
105representation of the commit history, similar to `git log
106--graph --oneline`.
107
108```
109| * | Add support for configuration file
110* | | simplify command parsing logic
111* | | Refactor parsers
112* | | Add basic tests
113* | | Merge remote-tracking branch 'origin/master' in...
114|\| |
115| * | add installation instructions for nix
116| * | switch to pancurses backendv0.2.2
117| * | bump to v0.2.2
118* | | Merge branch 'master' into feature/larger-names...
119|\| |
120| * | enable feature based compilation to support win...
121| * | remove dependency on rustc v1.45, bump to v0.2....
122| * | Merge branch 'feature/windows' of https://git...
123| |\ \
124| | * | add windows to github actions
125| | * | switch to crossterm backend
126| | * | Merge branch 'fix/duplicate-habits'
127| | |\ \
128| | | * | move duplicate check to command parsing blo...
129```
130
131**section-from-path**: This option paired with `scan-path`
132will automatically generate sections in your cgit index
133page, from the path to each repo. For example, the directory
134structure used to generate sections on [my cgit
135instance](https://git.peppe.rs) looks like this:
136
137```
138├── cli
139│ ├── dijo
140│ ├── eva
141│ ├── pista
142│ ├── taizen
143│ └── xcursorlocate
144├── config
145│ ├── dotfiles
146│ └── nixos
147├── fonts
148│ ├── curie
149│ └── scientifica
150├── languages
151│ └── lisk
152├── libs
153│ ├── cutlass
154│ └── fondant
155├── terminfo
156├── university
157│ └── furby
158└── web
159 └── isostatic
160```
161
162### Ease of use
163
164As I mentioned before, `cgit` is simply a view into your git
165repositories, you will have to manually create new
166repositories by entering your remote and using `git init
167--bare`. Here are a couple of scripts I wrote to perform
168actions on remotes, think of it as a smaller version of
169Github's `gh` program.
170
171You may save these scripts as `git-script-name` and drop
172them in your `$PATH`, and git will automatically add an
173alias called `script-name`, callable via:
174
175```
176git script-name
177```
178
179#### git-new-repo
180
181Creates a new repository on your remote,
182the first arg may be a path (section/repo-name) or just the
183repo name:
184
185```
186#! /usr/bin/env bash
187#
188# usage:
189# git new-repo section/repo-name
190#
191# example:
192# git new-repo fonts/scientifica
193# creates: user@remote:fonts/scientifica
194
195if [ $# -eq 0 ]; then
196 echo "requires an arg"
197 exit 1
198fi
199
200ssh user@remote git init --bare "$1";
201```
202
203
204#### git-set-desc
205
206To set a one line repository
207description. It simply copies the local `.git/description`,
208into `remote/description`. `cgit` displays the contents of
209this file on the index page:
210
211```
212#! /usr/bin/env bash
213#
214# usage:
215# enter repo description into .git/description and run:
216# git set-desc
217
218remote=$(git remote get-url --push origin)
219scp .git/description "$remote/description"
220```