From f33cfdadfef34c61cd72157c0828a5dca6b1598e Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Mon, 25 Jan 2016 01:36:59 -0800
Subject: [PATCH] Fix variable lookup order

Evaluator uses frames as a stack, so to find the most-recent variable
binding we have to iterate through it the reverse way. This fixes a bug
manifested by:

fn a(x)
 x + 20
end

fn b(x)
 a(x) + 20
end
---
 src/eval.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/eval.rs b/src/eval.rs
index 9490676..73bb9b4 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -51,7 +51,7 @@ impl Evaluator {
     }
 
     fn lookup_binding(&mut self, var: String) -> Option<Expression> {
-        for frame in self.frames.iter() {
+        for frame in self.frames.iter().rev() {
             match frame.map.get(&var) {
                 None => (),
                 Some(expr) => return Some(expr.clone()),