ランダムに並んだ「2」と「0」の列から「2020」を見つけてハイライトする。
年賀状のためにPostScriptで書いたものを、Haskellで書き直した。もっといろいろな書き方ができそう。シェルスクリプトとかでも書けそう。
module Main where
import System.Environment (getArgs)
import System.Random
import Data.List
scan2020 :: [Int] -> [[Int]]
scan2020 [] = []
scan2020 ls@(x:xs)
| isPrefixOf the2020 ls = the2020 : (scan2020 $ drop 4 ls)
| otherwise = [x] : scan2020 xs
where the2020 = [2, 0, 2, 0]
hl2020 :: [[Int]] -> [String]
hl2020 [] = []
hl2020 (x:xs)
| length x == 4 =
concat ["\ESC[31m", intercalate " " $ map show x, "\ESC[m"] : hl2020 xs
| otherwise = concatMap show x : hl2020 xs
main :: IO ()
main = do
a <- fmap (read . head) getArgs
s <- getStdGen
putStrLn $ intercalate " " $ hl2020 $ take a $ scan2020 $ twoandzero s
where
twoandzero s = map ((*2) . flip mod 2) (randoms s :: [Int])
