From f85d5ba0a00e25bf063b8f9c993c815490bc483a Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Fri, 11 Oct 2019 17:10:09 -0400
Subject: array-list: Add bounds checking to array-list-ref.

---
 chickadee/array-list.scm | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/chickadee/array-list.scm b/chickadee/array-list.scm
index dad0b8d..54a11e8 100644
--- a/chickadee/array-list.scm
+++ b/chickadee/array-list.scm
@@ -76,7 +76,9 @@
     (set-array-list-vector! array-list new-vec)))
 
 (define (array-list-ref array-list i)
-  (vector-ref (array-list-vector array-list) i))
+  (if (and (>= i 0) (< i (array-list-size array-list)))
+      (vector-ref (array-list-vector array-list) i)
+      (error "array list index out of bounds" i)))
 
 (define (array-list-set! array-list i x)
   (vector-set! (array-list-vector array-list) i x))
-- 
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