From 67e8b85a9f9b42acc896b44eb2ea1310e749f03a Mon Sep 17 00:00:00 2001
From: Peter Mikkelsen <peter@pmikkelsen.com>
Date: Wed, 30 Jun 2021 02:01:46 +0000
Subject: Treat the variable _ differently, in that it doesn't introduce a new
 binding

---
 eval.c     | 4 ++++
 example.pl | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/eval.c b/eval.c
index 854d69c..c755cf5 100644
--- a/eval.c
+++ b/eval.c
@@ -169,6 +169,10 @@ unify(Term *a, Term *b, Binding **bindings)
 				left = right;
 				right = tmp;
 			}
+
+			if(runestrcmp(left->text, L"_") == 0)
+				continue; /* _ doesn't introduce a new binding */
+
 			Binding *b = malloc(sizeof(Binding));
 			b->name = left->text;
 			b->nr = left->clausenr;
diff --git a/example.pl b/example.pl
index 64f08ab..74387b1 100644
--- a/example.pl
+++ b/example.pl
@@ -32,3 +32,5 @@ length([Head|Tail], suc(Length)) :-
 :- initialization(could_be_friends(bob, sam)).
 
 :- initialization(length([a,b,c,d], Len)).
+
+:- initialization(length(_,_)).
\ No newline at end of file
-- 
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