PrintDigit

main :: IO()
main = do
    printInfo

printInfo :: IO()
printInfo = do
    input <- getLine
    if input /= "End" then
        do
            let info = printDigit input
            putStrLn (show info)
            printInfo
    else
        putStr ""

printDigit :: String -> String
printDigit "0" = "Zero"
printDigit "1" = "One"
printDigit "2" = "Two"
printDigit "3" = "Three"
printDigit "4" = "Four"
printDigit "5" = "Five"
printDigit "6" = "Six"
printDigit "7" = "Seven"
printDigit "8" = "Eight"
printDigit "9" = "Nine"
printDigit _   = "Please only enter single digit positive numbers"

printDigit2 :: String -> String
printDigit2 n = case n of
            "0" -> "Zero"
            "1" -> "One"
            "2" -> "Two"
            "3" -> "Three"
            "4" -> "Four"
            "5" -> "Five"
            "6" -> "Six"
            "7" -> "Seven"
            "8" -> "Eight"
            "9" -> "Nine"
            _ -> "Please only enter single digit positive numbers"

printDigit3 :: Int -> String
printDigit3 n
    | n >= 0 && n <= 9 = list !! n
    | otherwise = "Please only enter single digit positive numbers"
    where
        list = ["Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine"]