On 12/13/06, Alfonso Acosta <alfonso.acosta at gmail.com> wrote: > deactivate :: Maybe(hd -> IO ()), According to the spec, NULL here means no-op. So instead of using Maybe, just set deactivate = \_ -> return () if you see NULL. -- Taral <taralx at gmail.com> "You can't prove anything." -- Gödel's Incompetence Theorem