import Prelude hiding (concatMap, unlines)


-- Prefix each line in a text by the line number:
enumerateLines0 :: String -> String
enumerateLines0 =  concat . map (++"\n")
                          . map (uncurry (++))
                          . zip (map (\n -> show n ++ ": ") [1 ..])
                          . lines

concatMap :: (a -> [b]) -> [a] -> [b]
concatMap f = concat . map f

-- Prefix each line in a text by the line number:
enumerateLines :: String -> String
enumerateLines =  unlines . map (uncurry (++))
                          . zip (map (\n -> show n ++ ": ") [1 ..])
                          . lines

unlines :: [String] -> String
unlines = concatMap (++"\n")