あみだくじ

amida.hs

import System.Random (randomRIO)
import Data.List (subsequences)
import Control.Applicative ((<$>))
import Control.Monad (replicateM)

main :: IO ()
main = test 4 10

test :: Int -> Int -> IO ()
test r c = genAmida r c >>= drawAmida

data AMIDA = AMIDA Int Int [[Int]] deriving Show

amidaRows n = tail $ subsequences [1..n]
validAmidaRows = filter pred . amidaRows
  where
    pred xs = notElem 1 $ zipWith (-) (tail xs) xs
 
genAmida :: Int -> Int -> IO AMIDA
genAmida row col = AMIDA row col <$> amida
  where
    amida = replicateM col $ (possibility !!) <$> randomRIO(0, length possibility - 1)
    possibility = validAmidaRows row

drawAmida :: AMIDA -> IO ()
drawAmida (AMIDA rn cn lines) = mapM_ aux lines
  where
    aux row = putStr "|" >> mapM_ (putStr . conv . (`elem` row)) [1..rn] >> putStrLn ""
    conv True = "---|"
    conv False = "   |"