shithub: pprolog

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Add length/2 and member/2

--- a/example.pl

+++ b/example.pl

@@ -24,6 +24,3 @@

 =(A,A).

-length([], zero).

-length([Head|Tail], suc(Length)) :-

-	length(Tail, Length).

--- a/stdlib.pl

+++ b/stdlib.pl

@@ -55,3 +55,14 @@

 	A == B.

 A @>= B :-

 	A @> B.

+

+% List predicates

+

+length([], 0).

+length([_|Tail], Length) :-

+	length(Tail, Length0),

+	Length is Length + 1.

+

+member(X, [X|_]).

+member(X, [_|Tail]) :-

+	member(X, Tail).