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are interpreted; the mode declarations
is equivalent to
. It is accepted for compatibility reasons. The predicate predicate_property/2 reports arguments declared using
^-annotated goal of setof/3, bagof/3, aggregate/3 and aggregate/4. It is processed similar to `0', but leaving the
Each argument that is module-sensitive (i.e., marked 0..9,
) is qualified with the context module of the
caller if it is not already qualified. The implementation ensures that
the argument is passed as <module>:<term>,
where <module> is an atom denoting the name of a module
and <term> itself is not a
term where the first argument is an atom. Below is a simple declaration
and a number of queries.
:- meta_predicate meta(0, +). meta(Module:Term, _Arg) :- format('Module=~w, Term = ~q~n', [Module, Term]).
?- meta(test, x). Module=user, Term = test ?- meta(m1:test, x). Module=m1, Term = test ?- m2:meta(test, x). Module=m2, Term = test ?- m1:meta(m2:test, x). Module=m2, Term = test ?- meta(m1:m2:test, x). Module=m2, Term = test ?- meta(m1:42:test, x). Module=42, Term = test
The meta_predicate/1 declaration is the portable mechanism for defining meta-predicates and replaces the old SWI-Prolog specific mechanism provided by the deprecated predicates module_transparent/1, context_module/1 and strip_module/3. See also section 6.15.