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boole.scm
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1999-01-02
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#| -*-Scheme-*-
$Id: boole.scm,v 14.3 1999/01/02 06:11:34 cph Exp $
Copyright (c) 1988, 1999 Massachusetts Institute of Technology
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|#
;;;; Boolean Operations
;;; package: ()
(declare (usual-integrations))
(define-primitives not (false? not))
(define false #F)
(define true #T)
(define (boolean? object)
(or (eq? object #F)
(eq? object #T)))
(define (boolean=? x y)
(if x y (not y)))
(define (boolean/or . arguments)
(let loop ((arguments arguments))
(cond ((null? arguments) false)
((car arguments) true)
(else (loop (cdr arguments))))))
(define (boolean/and . arguments)
(let loop ((arguments arguments))
(cond ((null? arguments) true)
((car arguments) (loop (cdr arguments)))
(else false))))
(define (there-exists? items predicate)
(let loop ((items items))
(and (not (null? items))
(or (predicate (car items))
(loop (cdr items))))))
(define (for-all? items predicate)
(let loop ((items items))
(or (null? items)
(and (predicate (car items))
(loop (cdr items))))))