Raw I/O library proposal, second (more pragmatic) draft

[Ben Rudiak-Gould]

On Fri, 1 Aug 2003, Simon Marlow wrote:

> class InputStream s where
>       streamGet         :: s -> IO Word8
>       streamReadBuffer  :: s -> Integer -> Buffer -> IO ()
>       streamGetBuffer   :: s -> Integer -> IO ImmutableBuffer
>       streamGetContents :: s -> IO [Word8]
> 
> class OutputStream s where
>       streamPut         :: s -> Word8 -> IO ()
>       streamPuts        :: s -> [Word8] -> IO ()
>       streamWriteBuffer :: s -> Integer -> Buffer -> IO ()

Now that I think about it, we should parameterize these classes over the
input/output data type also. Then we could have

  filterInputStream ::
    (Storable a, Storable b, InputStream s a, InputStream t b) =>
      BlockRecoder a b -> s -> t

  filterOutputStream ::
    (Storable a, Storable b, OutputStream s a, OutputStream t b) =>
      BlockRecoder b a -> s -> t

Text streams would fit into this model. Plus, there are many useful stream
filters which don't go octet -> char or char -> octet, such as:

  packBitsLE, packBitsBE     :: BlockRecoder Bool Word8
  unpackBitsLE, unpackBitsBE :: BlockRecoder Word8 Bool
  zlibPack, zlibUnpack       :: BlockRecoder Word8 Word8
  recodeNewlines             :: NewlineFormat -> BlockRecoder Char Char
  serialize                  :: (Serializable a) => BlockRecoder a Word8
  unserialize                :: (Unserializable a) => BlockRecoder Word8 a


-- Ben