From 05c6f24c0b371a465a8735cfd1ac17c0394363cb Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Wed, 24 Mar 2021 13:05:05 +0530
Subject: allow minus operator, improve display for exprs

---
 src/lisp/expr.rs | 49 ++++++++++++++++++++++++++-----------------------
 src/lisp/lex.rs  |  7 ++++++-
 src/lisp/mod.rs  |  1 -
 3 files changed, 32 insertions(+), 25 deletions(-)

(limited to 'src/lisp')

diff --git a/src/lisp/expr.rs b/src/lisp/expr.rs
index adacc1c..651e41f 100644
--- a/src/lisp/expr.rs
+++ b/src/lisp/expr.rs
@@ -1,7 +1,30 @@
 use std::fmt;
 
 use crate::app::AppState;
-use crate::lisp::{error::LispError, number::LispNumber};
+use crate::lisp::{error::LispError, number::LispNumber, Environment};
+
+#[derive(Clone)]
+pub struct PrimitiveFunc {
+    pub arity: Option<usize>, // minimim arity
+    pub closure: fn(&[LispExpr], &mut AppState) -> Result<LispExpr, LispError>,
+}
+
+impl PrimitiveFunc {
+    pub fn call(&self, args: &[LispExpr], app: &mut AppState) -> Result<LispExpr, LispError> {
+        if let Some(arity) = self.arity {
+            if args.len() < arity {
+                return Err(LispError::EvalError);
+            }
+        }
+        (self.closure)(args, app)
+    }
+}
+
+#[derive(Clone)]
+pub struct LispFunction {
+    pub params: Vec<String>,
+    pub body: Vec<LispExpr>,
+}
 
 #[derive(Clone)]
 pub enum LispExpr {
@@ -21,23 +44,6 @@ pub enum LispExpr {
     Quote(Box<LispExpr>, u32),
 }
 
-#[derive(Clone)]
-pub struct PrimitiveFunc {
-    pub arity: Option<usize>,
-    pub closure: fn(&[LispExpr], &mut AppState) -> Result<LispExpr, LispError>,
-}
-
-impl PrimitiveFunc {
-    pub fn call(&self, args: &[LispExpr], app: &mut AppState) -> Result<LispExpr, LispError> {
-        if let Some(arity) = self.arity {
-            if args.len() < arity {
-                return Err(LispError::EvalError);
-            }
-        }
-        (self.closure)(args, app)
-    }
-}
-
 impl LispExpr {
     pub fn comma(self, n: u32) -> LispExpr {
         match self {
@@ -83,7 +89,7 @@ impl fmt::Display for LispExpr {
                     write!(f, " {} ", expr)?
                 }
             }
-            LispExpr::StringLit(s) => write!(f, "{:?}", s)?,
+            LispExpr::StringLit(s) => write!(f, "{}", s)?,
             LispExpr::BoolLit(b) => {
                 if *b {
                     write!(f, "#t")?
@@ -93,7 +99,7 @@ impl fmt::Display for LispExpr {
             }
             LispExpr::Ident(s) => write!(f, "{}", s)?,
             LispExpr::PrimitiveFunc(_) => write!(f, "<#primitive>")?,
-            LispExpr::Function(_) => write!(f, "<#procedure>")?,
+            LispExpr::Function(func) => write!(f, "<#lambda {}>", func.params.join(" "))?,
             LispExpr::Quasiquote(val, depth) => {
                 write!(f, "{}{}", "`".repeat(*depth as usize), val)?
             }
@@ -104,6 +110,3 @@ impl fmt::Display for LispExpr {
         Ok(())
     }
 }
-
-#[derive(Debug, PartialEq, Clone)]
-enum LispFunction {}
diff --git a/src/lisp/lex.rs b/src/lisp/lex.rs
index 30f49fa..a7b9586 100644
--- a/src/lisp/lex.rs
+++ b/src/lisp/lex.rs
@@ -115,11 +115,13 @@ impl<'a> Lexer<'a> {
 
 fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), LispError> {
     let mut dot = false;
+    let mut minus = false;
     let mut size = 0;
     let mut chars = input.chars();
 
     if let Some(v) = chars.next() {
         if v == '-' {
+            minus = true;
             size += 1;
             input = &input[1..];
         } else if v.is_digit(10) {
@@ -143,7 +145,10 @@ fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), LispError>
             return Err(LispError::ParseError);
         }
     }
-    let tok = if dot {
+
+    let tok = if size == 1 && minus {
+        Token::Name("-")
+    } else if dot {
         Token::Float(&input[..size])
     } else {
         Token::Integer(&input[..size])
diff --git a/src/lisp/mod.rs b/src/lisp/mod.rs
index 2a19314..dc08835 100644
--- a/src/lisp/mod.rs
+++ b/src/lisp/mod.rs
@@ -4,7 +4,6 @@ pub mod expr;
 pub mod lex;
 pub mod number;
 pub mod parse;
-#[macro_use]
 mod primitives;
 
 use std::collections::HashMap;
-- 
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