Into-quarters splitter (Me)

-- The app reads a column of lines of text from STDIN and splits the
-- column into four equal or almost equal parts with an empty line as a
-- separator.

import Data.List (intercalate)
import System.Exit (die)

splitIntoFour :: [a] -> [[a]]
splitIntoFour list = let
  l = length list
  q1 = div l 4
  q2 = div l 2 - q1
  q3 = div (l - div l 2) 2
  in
  if l < 4
  then
    map (:[]) list
  else
    [take q1 list, take q2 $ drop q1 list, take q3 $ drop (q1 + q2) list, drop (q1 + q2 + q3) list]

main :: IO ()
main = do
  input <- getContents
  if null input
    then
      die "No input!"
    else
      putStr $ unlines $ intercalate [""] (splitIntoFour $ lines input)