When binding two variables to eachother, always bind to the one with the lowest clause number

1 files changed, 5 insertions, 0 deletions

diff --git a/eval.c b/eval.c
index e490eb6..b300d11 100644
--- a/eval.c
+++ b/eval.c
@@ -194,6 +194,11 @@ unify(Term *a, Term *b, Binding **bindings)
 				left = right;
 				right = tmp;
 			}
+			if(left->tag == VariableTerm && right->tag == VariableTerm && right->clausenr > left->clausenr){
+				Term *tmp = left;
+				left = right;
+				right = tmp;
+			}
 
 			if(runestrcmp(left->text, L"_") == 0)
 				continue; /* _ doesn't introduce a new binding */