What version of GHC are you using?
Your code works for me in rxvt in Cygwin, with GHC 6.4.1. But I remember having
that same problem earlier (in some earlier GHC version, so it may be fixed by now).
The solution was to run hFlush after each putStr, like so:
import System.IO (hFlush, stdout)
do putStr "..."
hHlush stdout
...
If I remember correctly, the problem only occurred in GHCi and Hugs -- not when
compiling the code.
/ Emil
Maurício skrev:
You're right... I was running the example in rxvt, in cygwin. Now I
tried in Windows command shell and it works.
Thanks,
Maurício
Cale Gibbard wrote:
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
System.IO.
- Cale
On 17/02/06, Maurício <[EMAIL PROTECTED]> 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?
Thanks,
Maurício
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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