backtrack: Added cut-amb

diff --git a/extra/backtrack/backtrack.factor b/extra/backtrack/backtrack.factor
index 3c1a79412118bd5891a2fab0b58da82e0c3e2b0a..db2c50173c9f8c85c7585fb448d4e9e5bf4bb9f9 100755 (executable)
--- a/extra/backtrack/backtrack.factor
+++ b/extra/backtrack/backtrack.factor
@@ -66,3 +66,5 @@ MACRO: amb-execute ( seq -- quot )
         tri* if\r
     ] with-scope ; inline\r
 \r
+: cut-amb ( -- )\r
+    f failure set ;\r