--- a/src/Pure/more_thm.ML Tue Apr 24 22:22:25 2018 +0100
+++ b/src/Pure/more_thm.ML Wed Apr 25 14:13:44 2018 +0200
@@ -603,10 +603,9 @@
(* unofficial theorem names *)
+fun has_name_hint thm = AList.defined (op =) (Thm.get_tags thm) Markup.nameN;
fun the_name_hint thm = the (AList.lookup (op =) (Thm.get_tags thm) Markup.nameN);
-
-val has_name_hint = can the_name_hint;
-val get_name_hint = the_default "??.unknown" o try the_name_hint;
+fun get_name_hint thm = if has_name_hint thm then the_name_hint thm else "??.unknown";
fun put_name_hint name = untag_rule Markup.nameN #> tag_rule (Markup.nameN, name);