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succeeds exactly once.
true/0
true/0 succeeds exactly once.
Examples
| write('this is going to succeed'), true. | Succeeds with output on the current outputstream 'this is going to succeed'. |
| integer(a),true. | Fails. |
Standard
This predicate is part of the ISO-Prolog Standard.
See also
abort/0, break/0, fail/0, call/1, fcall/1, catch/3, ','(conjunction)/2, '!'(cut)/0, ';'(disjunction)/2, halt/0/1, '->'(if-then)/2, ';'(if-then-else)/2, '\+'(not provable)/1, once/1, repeat/0, throw/1.
| document: http://www.ifcomputer.co.jp/MINERVA/Manual/Reference/Predicates/logic_and_control/true/print_en.html published 2008/8/25 update 2001/2/7 (c) 1996-2006 IF Computer Japan | ||||||||
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