How do I write Push and Pop in Scheme?
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by kunjaan
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Published on 2009-06-25T00:20:26Z
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2010/06/08
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Right now I have
(define (push x a-list)
(set! a-list (cons a-list x)))
(define (pop a-list)
(let ((result (first a-list)))
(set! a-list (rest a-list))
result))
But I get this result:
Welcome to DrScheme, version 4.2 [3m].
Language: Module; memory limit: 256 megabytes.
> (define my-list (list 1 2 3))
> (push 4 my-list)
> my-list
(1 2 3)
> (pop my-list)
1
> my-list
(1 2 3)
What am I doing wrong? Is there a better way to write push so that the element is added at the end and pop so that the element gets deleted from the first?
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