PLOGHELP FUNCTOR                              Chris Mellish, August 1982
                                Revised by Kathryn Seifert  October 1986

Predicate whose arguments are unified with a term, its functor, and
arity.

    ?- functor(Term, Functor, Arity).

Keywords: term, functor, arity, structure


Term is a term whose functor is Functor and whose arity is Arity.  When
this predicate is called, either Term should be instantiated or both
Functor and Arity should be.

'functor' can be used to construct a term with a certain functor and
arity. For example:

    ?- functor(X, foo, 2).
    X = foo(_1, _2) ?

It can also be used to "examine" a given term:

    ?- functor(foo(a,b), Name, Arity).
    Name = foo
    Arity = 2 ?

-- RELATED DOCUMENTATION ----------------------------------------------

PLOGHELP * ARG
 Predicate which determines the Nth argument of a given term

PLOGHELP * UNIV
 Operator which makes a term from a list

PLOGHELP * DOLLAR
 Library package for using variables to hold predicate names
