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succeeds if the goal fails and fails if the goal succeeds.
\+(+Goal)
\+ +Goal
'\+'/1 makes negation by failure. That means it succeeds if Goal fails and fails if Goal succeeds.
Arguments
Goal goal
Examples
| \+fail. | Succeeds. |
| \+integer(4.76) | Succeeds. |
| \+((X=either;X=or)),X=neither_nor | Fails. |
Standard
This predicate is part of the ISO-Prolog Standard.
See also
abort/0, break/0, call/1, fcall/1, catch/3, ','(conjunction)/2, '!'(cut)/0, ';'(disjunction)/2, fail/0, true/0, halt/0/1, '->'(if-then)/2, ';'(if-then-else)/2, once/1, repeat/0, throw/1.
| document: http://www.ifcomputer.co.jp/MINERVA/Manual/Reference/Predicates/logic_and_control/not_provable/print_en.html published 2008/7/7 update 2001/2/7 (c) 1996-2006 IF Computer Japan | ||||||||
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