! (cut)
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: ! (cut)
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BAP Online Manuals : Library Reference : Library by Name : ! (cut)
Previous: Library by Name
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6.2.1. ! (cut)
affects backtracking
SYNOPSIS
!
SYNTAX
!
ARGUMENTS
(none)
DESCRIPTION
This is a standard prolog built-in. If a execution within a clause encounters a cut, the
system commits to all choices made since entering the parent goal. This means that no
other clauses of the predicate will be evaluated, and either this clause suceeds or the entire
predicate call fails.
The ! succeeds once and causes the parent goal to fail if encountered during
backtracking.
The !,fail combination is often used to indicate final failure of a predicate goal.
EXAMPLE
repeat, read(X), write(X),nl, X=ende, !,fail.
ERRORS
Always succeeds. No runtime errors.
LAYERS
prolog-process, client-server, object
RELATED PREDICATES
set_cut , cut , getbacktrack , cutbacktrack
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