chunk :: (Eq b) => [a] -> (a -> b) -> [(b, [a])]
chunk [] _ = []
chunk (x:xs) f =  let fx = f x
                      (h, t) = span ((==) fx . f) xs
                  in [(fx,(x:h))] ++ chunk t f



data ChunkType = Word | Blank deriving (Show, Eq)

chunkByBlank :: Char -> ChunkType
chunkByBlank ' ' =  Blank
chunkByBlank _ = Word

main = putStrLn . show $ chunk "Haskell is awesome!!" chunkByBlank
-- => [(Word,"Haskell"),(Blank," "),(Word,"is"),(Blank," "),(Word,"awesome!!")]