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meta(?Var)
Succeeds if Var is an attributed variable.
- Var
- Prolog term.
Description
Used to test whether Var is an attributed variable.
CAUTION: this test only detects the presence of any attribute, which is
usually not what is required. It is more common to check for the presence
of a particular attribute by using a matching clause of the form:
has_my_attribute(_{my_attr:Attr}) ?-
nonvar(Attr).
Modes and Determinism
Fail Conditions
Fails if Var is not an attributed variable
Examples
Success:
meta(X{a}).
suspend:(X>0), meta(X).
Fail:
meta(atom).
meta(X).
See Also
free / 1, type_of / 2, var / 1