54 lines
1.5 KiB
Racket
54 lines
1.5 KiB
Racket
;;;
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;;; <alist.rkt> ---- Association list functions
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;;; Time-stamp: <02/03/01 13:56:33 noel>
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;;;
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;;; Copyright (C) 2002 by Noel Welsh.
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;;;
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;;; This file is part of SRFI-1.
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;;; This SRFI-1 implementation is distributed under the same terms as
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;;; Racket.
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;;; Author: Noel Welsh <noelwelsh@yahoo.com>
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;; Commentary:
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;; Based on the reference implementation by Olin Shiver and hence:
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;; Copyright (c) 1998, 1999 by Olin Shivers. You may do as you please with
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;; this code as long as you do not remove this copyright notice or
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;; hold me liable for its use. Please send bug reports to shivers@ai.mit.edu.
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;; -Olin
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;; Olin Shivers verified that he is fine with redistributing this code
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;; under the LGPL. (Verified personally by Eli Barzilay.)
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#lang scheme/base
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(require (only-in "search.rkt" find))
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(provide (rename-out [my-assoc assoc])
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alist-cons
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alist-copy
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alist-delete
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#; alist-delete! ; lists are immutable
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)
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;; Extended from R4RS to take an optional comparison argument.
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(define (my-assoc x lis [= equal?])
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(find (lambda (entry) (= x (car entry))) lis))
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(define (alist-cons key datum alist) (cons (cons key datum) alist))
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(define (alist-copy alist)
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(map (lambda (elt) (cons (car elt) (cdr elt))) alist))
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(define (alist-delete key alist [= equal?])
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(filter (lambda (elt) (not (= key (car elt)))) alist))
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#; ; lists are immutable
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(define (alist-delete! key alist [= equal?])
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(filter! (lambda (elt) (not (= key (car elt)))) alist))
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;;; alist.rkt ends here
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