home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
OS/2 Shareware BBS: 10 Tools
/
10-Tools.zip
/
mitsch75.zip
/
scheme-7_5_17-src.zip
/
scheme-7.5.17
/
src
/
cref
/
mset.scm
< prev
next >
Wrap
Text File
|
1999-01-02
|
1KB
|
40 lines
#| -*-Scheme-*-
$Id: mset.scm,v 1.2 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.
|#
;;;; Multiset Operations
(declare (usual-integrations))
(define (multiset->set multiset)
(if (null? multiset)
'()
(let ((set (multiset->set (cdr multiset))))
(if (memq (car multiset) set)
set
(cons (car multiset) set)))))
(define (multiset-difference x y)
(if (null? y)
x
(let loop ((x x))
(cond ((null? x) '())
((memq (car x) y) (loop (cdr x)))
(else (cons (car x) (loop (cdr x))))))))