Formats input separated by tabs into columns

column.hs

module Main where

import Data.List (transpose, words, lines, unwords, unlines)
import Data.Text (justifyLeft, unpack, pack)

prettyText :: [[String]] -> [[String]]
prettyText inputRows =
  let colWidths = map (maximum . map length) (transpose inputRows)
      indentFn = map (\x -> unpack . justifyLeft (x+2) ' ' . pack) colWidths -- right-pad each elem by col width + 2
      in map (zipWith ($) indentFn) inputRows -- apply each column's padding to each element

main = do
  input <- getContents
  putStr $ unlines $ map unwords $ prettyText $ map words $ lines input