SWI-Prolog -- abolish/1

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

[ISO]abolish(:PredicateIndicator)

Removes all clauses of a predicate with functor Functor and arity Arity from the database. All predicate attributes (dynamic, multifile, index, etc.) are reset to their defaults. Abolishing an imported predicate only removes the import link; the predicate will keep its old definition in its definition module.

According to the ISO standard, abolish/1 can only be applied to dynamic procedures. This is odd, as for dealing with dynamic procedures there is already retract/1 and retractall/1. The abolish/1 predicate was introduced in DEC-10 Prolog precisely for dealing with static procedures. In SWI-Prolog, abolish/1 works on static procedures, unless the Prolog flag iso is set to true.

It is advised to use retractall/1 for erasing all clauses of a dynamic predicate.