Availability:C-language interface function
functor_t PL_new_functor(atom_t 
name, int arity)Returns a functor identifier, a handle for the name/arity pair. 
The returned handle is valid for the entire Prolog session. Future 
versions may garbage collect functors as part of atom garbage 
collection. Currently aborts the process with a fatal error on 
failure. Future versions may raise a resource exception and return
(atom_t)0.