Hi Günther, here is a solution with the Maybe Monad:
http://hpaste.org/fastcgi/hpaste.fcgi/view?id=6515#a6515 Matthias. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
