bunch of exercise solutions from sections 2.3, 2.4 and 2.5

[sicp.git] / src / sicp / ch2_3.rkt

diff --git a/src/sicp/ch2_3.rkt b/src/sicp/ch2_3.rkt
index fe94cf8e24faa5b6fd407b36b6972ba86e1842f6..81e4dadabf30901bb83f9a174c34e06540c45839 100644 (file)
--- a/src/sicp/ch2_3.rkt
+++ b/src/sicp/ch2_3.rkt
@@ -1,5 +1,10 @@
 #lang racket
 
+(define (memq item x)
+  (cond ((null? x) #f)
+        ((eq? item (car x)) x)
+        (else (memq item (cdr x)))))
+
 ;; leaf nodes
 (define (make-leaf leaf weight)
   (list 'leaf leaf weight))