SP_get_functor() #include <sicstus/sicstus.h>
int
SP_get_functor(SP_term_ref term,
SP_atom *name,
int *arity);
Assigns to *name and *arity the canonical representation
and arity of the principal functor of a Prolog compound
term. If the value of term is an atom, then that atom
is assigned to *name and 0 is assigned to *arity. This is
similar to calling functor/3 with the first argument
bound to a compound term or an atom and the second and
third arguments unbound.
Zero if the conversion fails (as far as failure can be detected), and a nonzero value otherwise.