guess_number.hs

import System.Random
import Control.Monad (when)

main :: IO ()
main = do
  gen <- getStdGen
  askForNumber gen


askForNumber :: StdGen -> IO ()
askForNumber gen = do
  let (randomNumber, newGen) = randomR (1, 10) gen :: (Int, StdGen)
  putStrLn "Which in the range from 1 to 10 am I thinking of?"
  numberString <- getLine
  when (not $ null numberString) $ do
    let number = read numberString
    if randomNumber == number
      then putStrLn "You are correct!"
      else putStrLn $ "Sorry, it was " ++  show randomNumber
    askForNumber newGen