Hi !,

I have the following program from “Learn You a Haskell” ( http://learnyouahaskell.com/input-and-output#randomness ). When i run this using runhaskell, code works perfectly fine. However, when i compile and run the binary file, code behaves differently.

Basically, in the following code, we print a line first and the read the line from stdin. This behavior works perfectly fine when using “runhaskell guess.hs”. But when i say “./guess”, i had to type in a number directly ( i.e. first prompt is skipped ).

btw.. i am using mac yosomite command terminal.

Any help greatly appreciated.. Thanks a lot in advance..

import System.Random

import Control.Monad(when)

main = do

  ranGen <- getStdGen

  let (rand,_) = randomR (1,10) ranGen :: (Int,StdGen)

  putStr "Guess a number between 1 and 10 : "

  numStr <- getLine

  when(not $ null numStr) $ do

    let num = read numStr

    if rand == num

      then putStrLn "Yuhaa!! you are right baby!"

      else putStrLn $ "Sorry dude!! it was " ++ show rand

    newStdGen

    main