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#| utils.jl -- misc functions
$Id: utils.jl,v 1.7 2000/07/29 10:44:07 john Exp $
Copyright (C) 2000 John Harper <john@dcs.warwick.ac.uk>
This file is part of librep.
librep 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, or (at your option)
any later version.
librep 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 Jade; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
|#
(define-structure scheme.utils
(export #f #t \#test
make-predicate
make-nil-predicate)
(open rep)
(defconst #f #f)
(defconst #t #t)
;; given a scheme boolean, convert to a rep boolean
(define (\#test value) (not (eq value #f)))
;; create a scheme predicate from the rep predicate PRED
(define (make-predicate pred)
(lambda args
(if (apply pred args) #t #f)))
;; create a scheme `pseudo-predicate' from the rep `pseudo-predicate'
;; PRED. `pseudo-predicate' means that it returns false or an
;; interesting non-false value
(define (make-nil-predicate pred)
(lambda args
(cond ((apply pred args)) (t #f)))))
|
