Word8-Based IO

21 Aug 2002

      Was there any kind of consensus emerging on this? Leaving aside what 
might be done with the Char-based functions (and people seem to think 
they're fine as is) I'd like to suggest the following:

* System.IO: addition of new Word8-based functions

  hGetOctet :: Handle -> IO Word8
  hLookAheadOctet :: Handle -> IO Word8
  hPutOctet :: Handle -> Word8 -> IO ()
  hPutArray :: Handle -> [Word8] -> IO ()
  hLazyGetArray :: Handle -> IO [Word8]

...as per hGetChar, hLookAhead, hPutChar, hPutStr and hGetContents.

  hGetArrayBlock :: Handle -> Int -> IO [Word8]
  hGetArrayReady :: Handle -> Int -> IO [Word8]

hGetArrayBlock would read so many octets from the handle, up to the EOF.
hGetArrayReady would read so many octets from the handle, up to the EOF 
or octets not ready. The semantics would be something like this:

  hGetArrayBlock h 0 = return [];
  hGetArrayBlock h n = do {
      eof <- hIsEOF h;
      if eof then return [] else do {
          first <- hGetOctet;
          rest <- hGetArrayBlock h (n - 1);
          return (first:rest);
      };
  };

  hGetArrayReady h 0 = return [];
  hGetArrayReady h n = do {
      ready <- hReady h;
      if not ready then return [] else do {
          first <- hGetOctet;
          rest <- hGetArrayReady h (n - 1);
          return (first:rest);
      };
  };

...but I expect they should be implemented natively.

  hSetFileSize :: Handle -> Integer -> IO ()

There's currently no way to set the size of a file. hSetFileSize would 
truncate the file or pad with zero octets.

* Network.Socket

The send & receive functions don't do any kind of character 
interpretation do they? I suggest these functions be given new types (and 
probably new names, as I suppose we'll need the old ones for 
compatibility):

  sendTo :: Socket -> [Word8] -> SockAddr -> IO Int
  recvFrom :: Socket -> Int -> IO ([Word8], Int, SockAddr)
  send :: Socket -> [Word8] -> IO Int
  recv :: Socket -> Int -> IO [Word8]

-- 
Ashley Yakeley, Seattle WA