exported print_tuple

--- a/src/Tools/Code/code_ml.ML	Wed Apr 28 16:56:18 2010 +0200
+++ b/src/Tools/Code/code_ml.ML	Wed Apr 28 16:56:19 2010 +0200
@@ -9,6 +9,8 @@
   val target_SML: string
   val evaluation_code_of: theory -> string -> string
     -> Code_Thingol.naming -> Code_Thingol.program -> string list -> string * string option list
+  val print_tuple: (Code_Printer.fixity -> 'a -> Pretty.T)
+    -> Code_Printer.fixity -> 'a list -> Pretty.T option
   val setup: theory -> theory
 end;