X represents the name and arity of the predicate. Y represents the full class name of an implementation of org.projog.core.PredicateFactory.
This predicate provides an easy way to configure and extend the functionality of Projog - including adding functionality not possible to define in pure Prolog syntax.
Examples
?- pj_add_predicate(xyz/1, 'org.projog.core.predicate.builtin.compound.Call').
yes
?- xyz(true).
yes
?- xyz(repeat(3)).
yes;
yes;
yes
?- xyz(fail).
no