趣味编程：静夜思（Haskell版）

-- jys.hs

import Data.Map (fromListWith, toAscList)
import Data.List (intersperse)

verticalWriting text offset =
    let xxs = toAscList $ fromListWith (++) [(x `mod` offset, [y]) | (x, y) <- zip [0..] text]
    in  unlines [intersperse '|' xs | (_, xs) <- xxs]

main = putStr $ verticalWriting "床前明月光疑是地上霜举头望明月低头思故乡" 5

--低|举|疑|床
--头|头|是|前
--思|望|地|明
--故|明|上|月
--乡|月|霜|光