30 lines
567 B
Scheme
30 lines
567 B
Scheme
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; Copyright (c) 1994 by Richard Kelsey. See file COPYING.
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(define-data-type list
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(pair? (cons car cdr)
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(car integer car set-car!)
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(cdr list cdr set-cdr!))
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(null? null))
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(define (member? list x)
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(let loop ((list list))
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(cond ((null? list)
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#f)
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((= x (car list))
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#t)
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(else
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(loop (cdr list))))))
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(define (reverse! list)
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(if (or (null? list)
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(null? (cdr list)))
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list
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(let loop ((list list) (prev null))
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(let ((next (cdr list)))
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(set-cdr! list prev)
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(if (null? next)
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list
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(loop next list))))))
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