Thanks, Steve and Axel, for your help. I have got serial port IO working, but the solution is a bit ugly. My solution (below) works on Windows 2000, Hugs Nov 2003. It does not work with Windows 2000, GHI 5.04.2. Later tonight I will try it on Windows ME with the latest versions of GHC and Hugs.
The aim is to send a '?' character to a device on the serial port "COM2:". The device waits for a button to be pressed, then sends back a character. The test script then has to read this character from the serial port and display it. I first tried opening "COM2:" in ReadWriteMode, but this did not work with either GHCi or Hugs. For my second attempt, I open and close the file "COM2:" in the appropriate mode each time I send or receive a string. Its ugly, but it works. I am still interested in hearing from anyone who can get this working nicely with GHC. My code is below. > module SerialIO where > import IO Attempt 1: > test1 :: IO () > test1 > = do > com2 <- openFile "COM2:" ReadWriteMode > hSetBuffering com2 NoBuffering > isOpen <- hIsOpen com2 > isWritable <- hIsWritable com2 > isReadable <- hIsReadable com2 > putStrLn $ "hIsOpen = " ++ show isOpen > putStrLn $ "hIsWritable = " ++ show isWritable > putStrLn $ "hIsReadable = " ++ show isReadable > putStrLn "About to send..." > hPutStrLn com2 "?" > putStrLn "Reading..." > c <- hGetChar com2 > putStrLn [c] > putStrLn "Hoorah!" > hClose com2 Hugs Nov 2003 sends the character OK, but then... Reading... Program error: <handle>: IO.hGetChar: does not exist (file does not exist) GHCI 5.04.2 gives hIsWritable = False, then "No such file or directory" when it attempts to hPutChar. Attempt 2: open and close COM2 for each transmission > test2 :: IO () > test2 > = do > sendChar '?' > c <- receiveChar > putStrLn [c] > sendChar :: Char -> IO () > sendChar c > = do > com2 <- openFile "COM2:" WriteMode > hSetBuffering com2 NoBuffering > hPutChar com2 '?' > hClose com2 > receiveChar :: IO Char > receiveChar > = do > com2 <- openFile "COM2:" ReadMode > hSetBuffering com2 NoBuffering > c <- hGetChar com2 > return c GHCI fails as before, but Hugs works. _______________________________________________ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
