I can't get the following to work in Leksah - but it works OK in GHC. Can anyone spot the error? I wondered if it was becasue the libraries loaded are different - but I'm just a Haskell beginner ... I have: myGroupBy :: Int→ [a]→ [[a]] myGroupBy = takeWhile not . null . (unfoldr (Just . (splitAt 3))) and I am getting the error: Couldn't match expected type `Int' against inferred type `[a]' In the second argument of `(.)', namely `(splitAt 3)' In the first argument of `unfoldr', namely `(Just . (splitAt 3))' In the second argument of `(.)', namely `(unfoldr (Just . (splitAt 3)))' But I think that splitAt :: Int->[a]->([a],[a]) so: splitAt 3 :: [a]->([a], [a]) and: Just.(splitAt 3) :: [a]->Maybe ([a], [a]) which seems OK as the first argument of unfoldr: unfoldr :: (b-> Maybe(a,b))->b->[a] with the a and b of unfoldr being [a] and [a]. The mention of Int in the error makes me wonder if I've got the wrong splitAt - with the arguments reversed maybe. Any ideas? Thanks. N