2007/11/19, Ryan Ingram :

I am pretty sure that the constructor MaybeT is exactly what you are looking for.

newtype MaybeT m a = MaybeT (m (Maybe a))

therefore

MaybeT :: m (Maybe a) -> MaybeT m a

I swear I tried it. I swear.. Why didn't it worked than and it works now?? ;) Thank you very much for a tip. :) Thanks, Radek (who can go sleep now with clear mind). -- Codeside: http://codeside.org/ Przedszkole Miejskie nr 86 w Lodzi: http://www.pm86.pl/