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current_predicate/[1,2]
ISOcurrent_predicate(?PredSpec)
Unifies PredSpec with a predicate specifications of the form Name/Arity.
current_predicate(?Name, ?Term)
Unifies Name with the name of a user-defined predicate, and Term with the most general term corresponding to that predicate.
pred_spec
atom
callable
If you have loaded the predicates foo/1
and foo/3
into Prolog, then
current_predicate/2
would return the following:
| ?- current_predicate(foo, T). T = foo(_A) ; T = foo(_A,_B,_C) ; no
| ?- current_predicate(Name, Module:Term). | ?- current_predicate(Module:PredSpec).
current_predicate/[1,2]
only succeeds for those predicates that are
defined in the module. It fails for those predicates that are imported
into a module.
| ?- current_predicate(m:P).
will backtrack through all predicates P
that are defined in module m
.
To backtrack through all predicates imported by a module use
predicate_property/2
(see ref-lps-ove).
To find out whether a predicate is built-in, use
predicate_property/2
.
% Is there a callable predicate named gc
?
| ?- current_predicate(gc, Term).
no
| ?- predicate_property(gc, Prop)
Prop = built_in
instantiation_error
type_error
in PredSpec
current_predicate/1
is part of the ISO Prolog standard; current_predicate/2
is not.
predicate_property/2
, ref-lps-ove.