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 mech...@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 _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
