Quote predicate name for abolish/1

1 files changed, 2 insertions, 2 deletions

diff --git a/prolog/engine.py b/prolog/engine.py
index ea9b19a..8ad8bfa 100644
--- a/prolog/engine.py
+++ b/prolog/engine.py
@@ -284,13 +284,13 @@ class PrologEngine(object):
             name = Term()
             arity = Term()
             self.call('functor/3', [term, name, arity])
-            return '{}/{}'.format(name, arity)
+            return "'{}'/{}".format(name, arity)
 
         fid = PL_open_foreign_frame()
         clause = Term(clause)
         functor = main_functor(clause)
         # Check whether [clause] is a rule or a fact.
-        if functor == ':-/2':
+        if functor == "':-'/2":
             # [clause] is a rule, return the main functor for the head.
             head = Term()
             self.call('arg/3', [Term(1), clause, head])