import swap prevents strange failure of SML code generator for datatypes

--- a/src/HOL/Finite_Set.thy	Fri Aug 13 10:38:28 2010 +0200
+++ b/src/HOL/Finite_Set.thy	Fri Aug 13 10:51:23 2010 +0200
@@ -6,7 +6,7 @@
 header {* Finite sets *}
 
 theory Finite_Set
-imports Power Option
+imports Option Power
 begin
 
 subsection {* Predicate for finite sets *}