searches clauses in the database of the public user-defines procedures.

clause(?Head, ?Body)

clause/2 searches in the database of the public user-defined predicates for clauses with a head which is unifiable with Head. By backtracking Head gets unified with the head of a clause and Body gets unified with its body.

Arguments

Head                   atom or compound term
Body                   term

Examples

Assume there exists a database with the following user-defined predicates:

language(english).
language(X) :- translate(X,Y), language(Y).
translate(english, japanese).



clause(language(A),Body). 
Succeeds with substitution A <- english and Body <- true. 

When backtracking it succeeds a second time with substitution A < V1
and Body <- (translate(V1,V2), language(V2)). 



Standard

This predicate is part of the ISO-Prolog Standard.