import Data.List as L formatLine :: [String] -> [String] formatLine x = map (\e -> e ++ [' ' | _ <- [length e..nb]]) x where nb = maximum $ map length x formatLines :: [[String]] -> [[String]] formatLines x = map formatLine x completeMatrix :: [[String]] -> [[String]] completeMatrix m = map (\e -> e ++ [""| _ <- [length e..nb]]) m where nb = maximum $ map length m column :: [[String]] -> [[String]] column x = L.transpose $ formatLines $ L.transpose $ completeMatrix x main = do content <- getContents putStr $ unlines $ map unwords $ column $ map words $ lines content