password.hs

password.hs

import System.Random
import System.Environment
import Data.Maybe

main = do
    arg <- getArgs
    gen <- newStdGen
    putStrLn $ fromMaybe "" $ listToMaybe arg >>= (return . (password gen) . read)
    -- putStrLn . (password gen) $ fromMaybe 0 $ listToMaybe arg >>= return . read
    -- putStrLn . (password gen) . read $ fromMaybe "0" $ listToMaybe arg
    where
        characters = ['0'..'9']++['a'..'z']++['A'..'Z']++['!','$','%','@','#']
        password g x = take x $ zipWith (!!) (repeat characters) $ randomRs (0, (length characters) - 1) g