Hi, first I like to thank all of you guys - it really helps! I am still on a same chapter with higher order functions and this function is also confusing. But before i even define this function i am getting the type error - i don't know why? So i wrote the simpler one like: filterAlpha :: (a -> Bool) -> [a] -> [a] filterAlpha f [] = [] filterAlpha f (x:xs) |f x = x : filterAlpha xs |otherwise = filterAlpha xs and i am getting this error message: Type error in application Expression :filterAlpha xs Type : [b] Dous not match : a -> Bool To even my very little knowledge i think that this should work. What am i doing wrong? Thanks again -- View this message in context: http://www.nabble.com/filterFirst-tf4131377.html#a11749336 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.