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66 lines
2 KiB
Scheme
66 lines
2 KiB
Scheme
;;;"alist.scm", alist functions for Scheme.
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;;;Copyright (c) 1992, 1993 Aubrey Jaffer
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;
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;Permission to copy this software, to redistribute it, and to use it
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;for any purpose is granted, subject to the following restrictions and
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;understandings.
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;
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;1. Any copy made of this software must include this copyright notice
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;in full.
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;
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;2. I have made no warrantee or representation that the operation of
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;this software will be error-free, and I am under no obligation to
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;provide any services, by way of maintenance, update, or otherwise.
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;
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;3. In conjunction with products arising from the use of this
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;material, there shall be no use of my name in any advertising,
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;promotional, or sales literature without prior written consent in
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;each case.
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(define (predicate->asso pred)
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(cond ((eq? eq? pred) assq)
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((eq? = pred) assv)
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((eq? eqv? pred) assv)
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((eq? char=? pred) assv)
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((eq? equal? pred) assoc)
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((eq? string=? pred) assoc)
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(else (lambda (key alist)
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(let l ((al alist))
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(cond ((null? al) #f)
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((pred key (caar al)) (car al))
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(else (l (cdr al)))))))))
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(define (alist-inquirer pred)
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(let ((assofun (predicate->asso pred)))
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(lambda (alist key)
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(let ((pair (assofun key alist)))
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(and pair (cdr pair))))))
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(define (alist-associator pred)
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(let ((assofun (predicate->asso pred)))
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(lambda (alist key val)
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(let* ((pair (assofun key alist)))
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(cond (pair (set-cdr! pair val)
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alist)
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(else (cons (cons key val) alist)))))))
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(define (alist-remover pred)
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(lambda (alist key)
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(cond ((null? alist) alist)
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((pred key (caar alist)) (cdr alist))
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((null? (cdr alist)) alist)
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((pred key (caadr alist))
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(set-cdr! alist (cddr alist)) alist)
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(else
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(let l ((al (cdr alist)))
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(cond ((null? (cdr al)) alist)
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((pred key (caadr al))
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(set-cdr! al (cddr al)) alist)
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(else (l (cdr al)))))))))
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(define (alist-map proc alist)
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(map (lambda (pair) (cons (car pair) (proc (car pair) (cdr pair))))
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alist))
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(define (alist-for-each proc alist)
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(for-each (lambda (pair) (proc (car pair) (cdr pair))) alist))
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