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2013-04-11 01:07:29 -07:00 · 2013-04-11 01:07:29 -07:00 · 68f8f3e56b
commit 68f8f3e56b
parent b83f433714
14735 changed files with 178959 additions and 0 deletions
--- a/Task/Stack/Scheme/stack.ss
+++ b/Task/Stack/Scheme/stack.ss
@ -0,0 +1,15 @@
+(define (make-stack)
+  (let ((st '()))
+    (lambda (message . args)
+      (case message
+        ((empty?) (null? st))
+        ((top) (if (null? st)
+                   'empty
+                   (car st)))
+        ((push) (set! st (cons (car args) st)))
+        ((pop) (if (null? st)
+                   'empty
+                   (let ((result (car st)))
+                     (set! st (cdr st))
+                     result)))
+        (else 'badmsg)))))