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snatches errors generated during the execution of a goal.
catch(+Goal, ?CatchMask, ?RecoverGoal)
catch/3 snatches errors which are unifiable by CatchMask and generated during the execution of Goal, stops the execution of Goal and executes RecoverGoal. An error can be generated either in the program (see throw/1) or by the processor.
Arguments
Goal goal CatchMask term RecoverGoal goal
Examples
| X=throw(write('ok')), catch(X,Y,write('error')). | Succeeds with substitution X <- throw(write(ok)), Y <- write(ok) and executes write(error). |
| X=write(ok), catch(X,Y,write(error)). | Succeeds with substitution X <- write(ok), Y <- _735 and executes write(ok) |
Standard
This predicate is part of the ISO-Prolog Standard.
See also
abort/0, break/0, call/1, fcall/1, ','(conjunction)/2, '!'(cut)/0, ';'(disjunction)/2, fail/0, true/0, 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/catch/print_en.html published 2008/9/1 update 2001/2/7 (c) 1996-2006 IF Computer Japan | ||||||||
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