[Haskell-cafe] Re: Unexpected results with simple IO

[Maurício]

   I'm also using GHC 6.4.1 and rxvt v2.7.10. The problem does occur in 
compiled code, but everything is OK in ghci!
   hFlush stdout did solve the problem, as expected.
   I've just started using rxvt. If you have tips on how to make ghci 
work well with rxvt, please share them with me (for instance, how to set 
the top arrow to repeat the last line, instead of moving the cursor one 
live above. I don't understand very well how those applications handle 
keyboard).

   Best,
   Maurício

Emil Axelsson wrote:
> 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 <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?
>>>>
>>>>   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
>>>>
>>>> _______________________________________________
>>>> Haskell-Cafe mailing list
>>>> Haskell-Cafe at haskell.org
>>>> http://www.haskell.org/mailman/listinfo/haskell-cafe
>>>>
>>
>> _______________________________________________
>> Haskell-Cafe mailing list
>> Haskell-Cafe at haskell.org
>> http://www.haskell.org/mailman/listinfo/haskell-cafe