Availability:built-in
functor(?Term,
?Name, ?Arity, ?Type)As functor/3,
but designed to work with zero-arity terms (e.g.,
a(), see section
5). Type is one of atom,
compound, callable or atomic. Type
must be instantiated if Name is an atom and Arity
is 0 (zero). In other cases Type may be a variable. This
predicate is true if Term (either initially or after haveing
been created from Name and Type) and Type
are related as below
- If Term is compound (including zero-arity compounds),
Type must be
compound or callable.
If
Type is unbound is is unified with compound.
- If Term is an atom, Type must be
atom
or callable. If Type is unbound is is unified
with
atom.
- Else Type is unified with
atomic.
This predicate provides a safe round trip for zero-arity
compounds and atoms. It can also be used as a variant of functor/3
that only processes compound or callable terms. See also compound/1,
callable/1
and compound_name_arity/3.
