[Haskell-cafe] Unexpected results with simple IO
briqueabraque at yahoo.com
Fri Feb 17 15:40:26 EST 2006
Dear Haskell users,
I have a problem using IO. The small test program below asks the user
to guess from a list of random numbers between 1 and 10. Everything
works well excepts for one problem: all the messages ("Guess a
number...", "Right..." and "Wrong...") are printed after the program
finishes, i.e., I have to use it blind. I'm afraid I misunderstand
something important about lazyness or monads... What am I doing wrong?
module Main where
main = do
r_gen <- getStdGen --random generator
let r_list = (randomRs (1,10) r_gen) --random list
guess_loop (r:r_others) = do
putStrLn "Guess a number between 1 and 10:"
n <- readLn
putStrLn "Right! :)"
putStrLn "Wrong... :("
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