src/Pure/type_infer.ML

--- a/src/Pure/type_infer.ML	Tue Sep 20 08:20:22 2005 +0200
+++ b/src/Pure/type_infer.ML	Tue Sep 20 08:21:49 2005 +0200
@@ -452,7 +452,7 @@
       xi = xi' andalso Type.eq_sort tsig (S, S');
 
     val env = gen_distinct eq (map (apsnd map_sort) raw_env);
-    val _ = (case gen_duplicates eq_fst env of [] => ()
+    val _ = (case gen_duplicates (eq_fst (op =)) env of [] => ()
       | dups => error ("Inconsistent sort constraints for type variable(s) "
           ^ commas_quote (map (Syntax.string_of_vname' o fst) dups)));