From 6dc5eb710c27a3fee4a132763c106c5ce16f72ab Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Sat, 1 Aug 2020 16:37:25 +0530
Subject: add new post: Gripes with Go

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+You've read a lot of posts about the shortcomings of the Go
+programming language, so what's one more.
+
+ 1. [Lack of sum types](#lack-of-sum-types)
+ 2. [Type assertions](#type-assertions)
+ 3. [Date and Time](#date-and-time)
+ 4. [Statements over Expressions](#statements-over-expressions)
+ 5. [Erroring out on unused variables](#erroring-out-on-unused-variables)
+ 6. [Error handling](#error-handling)
+
+### Lack of Sum types
+
+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 `enum` type in C. Go
+lacks `enum` types unfortunately, and you are forced to
+resort to crafting your own substitute.
+
+A type to represent gender for example:
+
+```go
+type Gender int
+
+const (
+    Male Gender = iota  // assigns Male to 0
+    Female              // assigns Female to 1
+    Other               // assigns Other to 2
+)
+
+fmt.Println("My gender is ", Male)
+// My gender is 0
+// Oops! We have to implement String() for Gender ...
+
+func (g Gender) String() string {
+    switch (g) {
+    case 0: return "Male"
+    case 1: return "Female"
+    default: return "Other"
+    }
+}
+
+// You can accidentally do stupid stuff like:
+gender := Male + 1
+```
+
+The Haskell equivalent of the same:
+
+```haskell
+data Gender = Male
+            | Female
+            | Other
+            deriving (Show)
+
+print $ "My gender is " ++ (show Male)
+```
+
+### Type Assertions
+
+A downcast with an optional error check? What could go
+wrong?
+
+Type assertions in Go allow you to do:
+
+```go
+var x interface{} = 7
+y, goodToGo := x.(int)
+if goodToGo {
+    fmt.Println(y)
+}
+```
+
+The error check however is optional:
+
+```go
+var x interface{} = 7
+var y := x.(float64)
+fmt.Println(y)
+// results in a runtime error:
+// panic: interface conversion: interface {} is int, not float64
+```
+
+### Date and Time
+
+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:
+
+```
+Mon Jan 2 15:04:05 MST 2006
+```
+
+Which is the date produced when you write the first seven
+natural numbers like so:
+
+```
+01/02 03:04:05 '06 -0700
+```
+
+Parsing a string in `YYYY-MM-DD` format would look something
+like:
+
+```go
+const layout = "2006-01-02"
+time.Parse(layout, "2020-08-01")
+```
+
+This so-called "intuitive" method of formatting dates
+doesn't allow you to print `0000 hrs` as `2400 hrs`, it
+doesn't allow you to omit the leading zero in 24 hour
+formats. It is rife with inconveniences, if only there were
+a [tried and
+tested](https://man7.org/linux/man-pages/man3/strftime.3.html)
+date formatting convention ...
+
+### Statements over Expressions
+
+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.
+
+Rust allows you to create local namespaces, and treats
+blocks (`{}`) as expressions:
+
+```rust
+let twenty_seven = {
+    let three = 1 + 2;
+    let nine = three * three;
+    nine * three
+};
+```
+
+The Go equivalent of the same:
+
+```go
+twenty_seven := nil
+
+three := 1 + 2
+nine := three * three
+twenty_seven = nine * three
+```
+
+
+### Erroring out on unused variables
+
+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.
+
+### Error handling
+
+```go
+if err != nil { ... }
+```
+
+Need I say more? I will, for good measure:
+
+1. Error handling is optional
+2. Errors are propagated via a clunky `if` + `return` statement
+
+I prefer Haskell's "Monadic" error handling, which is
+employed by Rust as well:
+
+```rust
+// 1. error handling is compulsory
+// 2. errors are propagated with the `?` operator
+fn foo() -> Result<String, io::Error> {
+    let mut f = File::open("foo.txt")?; // return here if error
+    let mut s = String::new();
+
+    f.read_to_string(&mut s)?; // return here if error
+
+    Ok(s) // all good, return the value inside a `Result` context
+}
+```
+
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