手続き型言語Haskell

q5.hs

import Control.Monad (forM_)
import Data.Functor ((<$>))

main = do
  putStrLn "input natural number"
  n <- read <$> getLine
  putChar '\n'
  forM_ [n, n-1 .. 1] $ \i -> do
    forM_ [i, i-1 .. 1] $ \j -> do
      putStr $ show j
    putChar '\n'