On 01/12/2012 07:53 PM, Serge D. Mechveliani wrote:
[...]
For the "to-A" part writen in C (instead of Haskell), this interface loop works all right. With Haskell, I manage to process only a single string in the loop, and then it ends with an error.
Main.hs is given below.
I never dealt with such an IO in Haskell. Can you, please, fix the code or give comments?
Please, copy the response to mechvel@botik.ru (I am not in the list).
[...] ------------------------------------------------------------------- import System.IO (IOMode(..), IO(..), Handle, openFile, hPutStr, hGetLine, hFlush) import System.IO.Unsafe (unsafePerformIO)
dir = showString "/home/mechvel/ghc/axiomInterface/byLowerLevel/"
toA_IO = openFile (dir "toA") WriteMode :: IO Handle fromA_IO = openFile (dir "fromA") ReadMode -- used as global values toA = unsafePerformIO toA_IO -- fromA = unsafePerformIO fromA_IO --
axiomIO :: String -> IO String axiomIO str = do hPutStr toA str hFlush toA hGetLine fromA
axiom :: String -> String -> String axiom str = showString (unsafePerformIO $ axiomIO str)
-- Examples of usage --------------------------------------------
tl;dr, but did you try to write your program without using unsafePerformIO? It's "considered harmful" for a reason. Cheers, Steffen