--- a/ProgTutorial/Base.thy	Sun Mar 07 21:15:05 2010 +0100
+++ b/ProgTutorial/Base.thy	Wed Apr 07 11:12:12 2010 +0200
@@ -20,7 +20,7 @@
 (* they also write the code into a separate file  *)
 
 ML {*
-val (filename, setup_filename) = Attrib.config_string "filename" "File_Code.ML"
+val (filename, setup_filename) = Attrib.config_string "filename" (K "File_Code.ML")
 *}
 
 setup {* setup_filename *}