[Haskell-cafe] Unexpected results with simple IO
cgibbard at gmail.com
Fri Feb 17 15:54:05 EST 2006
That doesn't happen for me at all, it works just fine. Maybe it's
something wrong with your terminal? You could possibly try playing
with the buffering settings on stdout, using hSetBuffering in
On 17/02/06, Maurício <briqueabraque at yahoo.com> wrote:
> 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
> import Random
> main = do
> r_gen <- getStdGen --random generator
> let r_list = (randomRs (1,10) r_gen) --random list
> guess_loop (r_list)
> guess_loop (r:r_others) = do
> putStrLn "Guess a number between 1 and 10:"
> n <- readLn
> if n==r
> then do
> putStrLn "Right! :)"
> return ()
> else do
> putStrLn "Wrong... :("
> guess_loop r_others
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