--- a/src/HOL/Library/Countable.thy Sun Apr 12 11:38:05 2015 +0200
+++ b/src/HOL/Library/Countable.thy Sun Apr 12 12:07:48 2015 +0200
@@ -202,9 +202,9 @@
ML {*
fun countable_datatype_tac ctxt st =
- HEADGOAL (old_countable_datatype_tac ctxt) st
- handle exn =>
- if Exn.is_interrupt exn then reraise exn else BNF_LFP_Countable.countable_datatype_tac ctxt st;
+ (case try (fn () => HEADGOAL (old_countable_datatype_tac ctxt) st) () of
+ SOME res => res
+ | NONE => BNF_LFP_Countable.countable_datatype_tac ctxt st);
(* compatibility *)
fun countable_tac ctxt =