From 95f874fe29b84394748d660a536a516277184288 Mon Sep 17 00:00:00 2001
From: Peter Mikkelsen <peter@pmikkelsen.com>
Date: Tue, 6 Jul 2021 21:54:59 +0000
Subject: Add list module

---
 lists.pl | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 lists.pl

(limited to 'lists.pl')

diff --git a/lists.pl b/lists.pl
new file mode 100644
index 0000000..ee75110
--- /dev/null
+++ b/lists.pl
@@ -0,0 +1,16 @@
+:- module(lists, []).
+
+% List predicates
+
+length([], 0).
+length([_|Tail], Length) :-
+	length(Tail, Length0),
+	Length is Length0 + 1.
+
+member(X, [X|_]).
+member(X, [_|Tail]) :-
+	member(X, Tail).
+
+append([], Ys, Ys).
+append([X|Xs], Ys, [X|Rest]) :-
+	append(Xs, Ys, Rest).
-- 
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