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