> spanLines :: String -> [String]
> spanLines "" = []
> spanLines s  = let (l, s') = span' (/= '\n') s
>                in  l : case s' of
>                         []      -> []
>                         (_:s'') -> spanLines s''

> span' p []            = ([],[])
> span' p xs@(x:xs')
>          | p x       = (x:ys, zs)
>          | otherwise = ([],xs)
>                        where ~(ys,zs) = span' p xs'

> main = interact (unlines . spanLines)