[Haskell-cafe] Data.ByteString.Lazy.ByteString vs Data.ByteString.Lazy.Internal.ByteString

[Daniel Fischer]

On Monday 14 March 2011 05:45:04, C K Kashyap wrote:
> Thanks Brandon,
> 
> data Endian = Big | Little
> data Size = Eight | Sixteen | ThirtyTwo | SixtyFour
> type EncTuple = (Int,Size,Endian)
> 
> My requirement is to write encode :: [EncTuple] -> ByteString

Looks like a job for Data.Binary.

> I'd like to use it with just the libraries that are part of the platform

I don't know whether binary is in the platform, though (but I expect it to 
be).

> - and I am not a fan of using the internal stuff :)
> I'd appreciate it very much if you could give me a sample.

instance Binary Endian where
    put Big = putWord8 0
    put Little = putWord8 1
    get = do
      w <- getWord8
      case w of
        0 -> return Big
        1 -> return Little
        _ -> error ("Bad Endian tag: " ++ show w)

instance Binary Size where
    put Eight = putWord8 8
    put Sixteen = putWord8 16
    ...
    get = do
      w <- getWord8
      case w of
        8 -> return 8
        ...

putAux Eight _ i = putWord8 (fromIntegral i)
putAux Sixteen Big i = putWord16be (fromIntegral i)
...