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 ++++++++++++++++++++++++++-----------------------
 1 file changed, 26 insertions(+), 23 deletions(-)

(limited to 'src/lisp/expr.rs')

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 {}
-- 
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