Hello, At <http://www.cs.kun.nl/~clean/wrapdebug.html> you can now download the WrapDebug package. It provides debugging functions similar to the trace function in StdDebug, with two main advantages: 1) you don't have to define toString for the values you want to print; 2) you can control the amount of debugging output. Cheers, Ronny Wichers Schreur