SWI-Prolog -- copy_predicate

Documentation
- Reference manual
  - Built-in Predicates
    - Database
      - Managing (dynamic) predicates
        
        abolish/1
        
        abolish/2
        
        copy_predicate_clauses/2
        
        redefine_system_predicate/1
        
        retract/1
        
        retractall/1
        
        asserta/1
        
        assertz/1
        
        assert/1
        
        asserta/2
        
        assertz/2
        
        assert/2
- Packages

Availability:built-in

copy_predicate_clauses(:From, :To)

Copy all clauses of predicate From to To. The predicate To must be dynamic or undefined. If To is undefined, it is created as a dynamic predicate holding a copy of the clauses of From. If To is a dynamic predicate, the clauses of From are added (as in assertz/1) to the clauses of To. To and From must have the same arity. Acts as if defined by the program below, but at a much better performance by avoiding decompilation and compilation.

copy_predicate_clauses(From, To) :-
        head(From, MF:FromHead),
        head(To, MT:ToHead),
        FromHead =.. [_|Args],
        ToHead =.. [_|Args],
        forall(clause(MF:FromHead, Body),
               assertz(MT:ToHead, Body)).

head(From, M:Head) :-
        strip_module(From, M, Name/Arity),
        functor(Head, Name, Arity).