Thanks for the help everyone,problem solved. Very stupid of me not to see that tree instead of empty would solve the problem.
As for the 'other' errors, I wrote too fast and can't find the edit button. My first post contains the better implementation. John __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com _______________________________________________ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
