6 files changed, 37 insertions, 13 deletions

diff --git a/src/app.rs b/src/app.rs
index 7417dae..008b273 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -3,7 +3,7 @@ use crate::{
     command::CommandBox,
     consts::{colors::*, FONT_PATH},
     dither,
-    lisp::{env, lex::Lexer, parse::Parser, Environment},
+    lisp::{eval, lex::Lexer, parse::Parser, Environment},
     message::Message,
     rect,
     symmetry::Symmetry,
@@ -13,7 +13,6 @@ use crate::{
 
 use std::{convert::From, fs::File, io::prelude::*};
 
-use log::{info, warn};
 use obi::Image;
 use sdl2::{
     event::Event,
@@ -281,7 +280,7 @@ impl<'ctx> AppState<'ctx> {
         let lisp_expr = &self.command_box.text;
         let mut parser = Parser::new(Lexer::new(lisp_expr, 0));
         let res = parser.parse_single_expr();
-        match env::eval(&res.unwrap(), self, None) {
+        match eval::eval(&res.unwrap(), self, None) {
             Ok(val) => {
                 self.message.text = format!("{}", val);
             }
@@ -519,7 +518,7 @@ impl<'ctx> AppState<'ctx> {
             symmetry: Default::default(),
             ttf_context,
             undo_stack: UndoStack::new(),
-            lisp_env: env::with_prelude(),
+            lisp_env: eval::with_prelude(),
             zoom: 5,
         }
     }
diff --git a/src/lisp/error.rs b/src/lisp/error.rs
index 7214753..99dec3b 100644
--- a/src/lisp/error.rs
+++ b/src/lisp/error.rs
@@ -1,5 +1,3 @@
-use crate::lisp::lex::Span;
-
 #[derive(Debug, PartialEq, Copy, Clone)]
 pub enum LispError {
     ParseError,
diff --git a/src/lisp/env.rs b/src/lisp/eval.rs
index c5ff6d3..63c963c 100644
--- a/src/lisp/env.rs
+++ b/src/lisp/eval.rs
@@ -9,8 +9,6 @@ use crate::{
     primitive,
 };
 
-use std::collections::HashMap;
-
 use log::{error, info};
 
 pub fn with_prelude() -> Environment {
@@ -106,6 +104,17 @@ pub fn with_prelude() -> Environment {
             Ok(args.into_iter().last().unwrap().clone())
         }
     });
+    primitive!(env, Some(2), "/", |args, _| {
+        if args.is_empty() || args.iter().any(|arg| !matches!(arg, LispExpr::Number(_))) {
+            Err(LispError::EvalError)
+        } else {
+            let mut acc = unwrap_number(&args[0]).clone();
+            for arg in args.into_iter().skip(1) {
+                acc = acc.div(*unwrap_number(&arg))?;
+            }
+            Ok(LispExpr::Number(acc))
+        }
+    });
     env
 }
 
diff --git a/src/lisp/expr.rs b/src/lisp/expr.rs
index 651e41f..40b39eb 100644
--- a/src/lisp/expr.rs
+++ b/src/lisp/expr.rs
@@ -1,7 +1,7 @@
 use std::fmt;
 
 use crate::app::AppState;
-use crate::lisp::{error::LispError, number::LispNumber, Environment};
+use crate::lisp::{error::LispError, number::LispNumber};
 
 #[derive(Clone)]
 pub struct PrimitiveFunc {
diff --git a/src/lisp/mod.rs b/src/lisp/mod.rs
index dc08835..a52baa0 100644
--- a/src/lisp/mod.rs
+++ b/src/lisp/mod.rs
@@ -1,5 +1,5 @@
-pub mod env;
 pub mod error;
+pub mod eval;
 pub mod expr;
 pub mod lex;
 pub mod number;
diff --git a/src/lisp/number.rs b/src/lisp/number.rs
index ddadbe6..18a41f7 100644
--- a/src/lisp/number.rs
+++ b/src/lisp/number.rs
@@ -1,14 +1,32 @@
 use std::{
-    fmt::*,
+    fmt,
     ops::{Add, Div, Mul, Sub},
 };
 
+use crate::lisp::error::LispError;
+
 #[derive(Debug, Copy, Clone)]
 pub enum LispNumber {
     Integer(i64),
     Float(f64),
 }
 
+impl LispNumber {
+    pub fn div(self, rhs: Self) -> Result<LispNumber, LispError> {
+        use LispNumber::*;
+        if rhs == Integer(0) || rhs == Float(0.) {
+            return Err(LispError::EvalError);
+        } else {
+            return Ok(match (self, rhs) {
+                (Integer(a), Integer(b)) => Float(a as f64 / b as f64),
+                (Float(a), Integer(b)) => Float(a / b as f64),
+                (Integer(a), Float(b)) => Float(a as f64 / b),
+                (Float(a), Float(b)) => Float(a / b),
+            });
+        }
+    }
+}
+
 impl Add for LispNumber {
     type Output = Self;
     fn add(self, rhs: Self) -> Self::Output {
@@ -60,8 +78,8 @@ impl PartialEq for LispNumber {
     }
 }
 
-impl Display for LispNumber {
-    fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+impl fmt::Display for LispNumber {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             LispNumber::Integer(v) => write!(f, "{}", v),
             LispNumber::Float(v) => write!(f, "{}", v),