From 3bb57f3982c8f73c5a5a44d2b3ac03e8d7913bf8 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Tue, 29 Sep 2020 11:30:11 -0400
Subject: array-list: Add array-list-fold procedure.

---
 chickadee/array-list.scm | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/chickadee/array-list.scm b/chickadee/array-list.scm
index 3b11ec1..5e2174c 100644
--- a/chickadee/array-list.scm
+++ b/chickadee/array-list.scm
@@ -30,7 +30,8 @@
             array-list-push!
             array-list-pop!
             array-list-clear!
-            array-list-for-each))
+            array-list-for-each
+            array-list-fold))
 
 (define-record-type <array-list>
   (%make-array-list vector size)
@@ -116,3 +117,12 @@
       (when (< i size)
         (proc i (vector-ref vec i))
         (loop (1+ i))))))
+
+(define (array-list-fold proc init array-list)
+  (let ((size (array-list-size array-list))
+        (vec (array-list-vector array-list)))
+    (let loop ((i 0)
+               (prev init))
+      (if (< i size)
+          (loop (1+ i) (proc i (vector-ref vec i) prev))
+          prev))))
-- 
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