BAP Online Manuals : Library Reference : Library by Name : exists
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6.2.47. exists

checks whether a predicate is globally accessible

SYNOPSIS

exists(queens(_))

SYNTAX

exists(Goal) (i)

ARGUMENTS

void(Goal) (i) call to predicate to be checked out

DESCRIPTION

Tests whether a predicate is currently defined in the global symbol table of the node. Succeeds if the predicate with an argument count fitting the Goal is defined, fails otherwise.

EXAMPLE

read(X),
( exists(X),call(X),! ; write(X," does not exists!")nl ).

ERRORS

No runtime errors.

LAYERS

prolog-process, client-server, object

RELATED PREDICATES

call , exec , xcall


BAP Online Manuals : Library Reference : Library by Name : exists
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