src/Pure/Isar/context_rules.ML

   (elimK, "elimination rules (elim)"),
   (intro_queryK, "extra introduction rules (intro?)"),
   (elim_queryK, "extra elimination rules (elim?)")];
 
 val rule_kinds = map #1 kind_names;
-val rule_indexes = gen_distinct (op =) (map #1 rule_kinds);
+val rule_indexes = distinct (op =) (map #1 rule_kinds);
 
 
 (* context data *)
 
 type netpair = ((int * int) * (bool * thm)) Net.net * ((int * int) * (bool * thm)) Net.net;