====== Clauses displaying ======
{{tag>knowledge_base}}
===== Description =====
Showing all clause which define predicate

**Source**:  PROLOG str. 101 Wydawnictwo PLJ Warszawa 1991 ISBN 83-85190-63-5
===== Download =====
Program source code: {{clauses_displaying.pl}}
===== Listing =====
<code prolog>
dlugosc([], 0).
dlugosc([H|T], L) :- dlugosc(T, Y), L is Y + 1.

list1(X) :- clause(X, Y), klauzula(X, Y), write('.'), nl, fail.
list1(X).

klauzula(X, true) :- !, write(X).
klauzula(X, Y) :- write(X), write(' :- '), write(Y).

test :- list1(dlugosc(_, _)).</code>
===== Comments =====