Ptr-base send/receive functions

[VyacheslavHashov]

With these signatures or similar:

send :: Socket f t p -> Ptr Word8 -> Int -> MessageFlags -> IO Int

receive :: Socket f t p -> Ptr Word8 -> Int -> MessageFlags -> IO BS.ByteString

They might be useful in the following scenarios:

• Send. The user has a buffer that willing to send and there is no reason to wrap it in ByteString.
• Receive. The user has already allocated a buffer and receiving in it directly prevents extra allocation/copy.

[VyacheslavHashov]

There is already System.Socket.Unsafe.

[VyacheslavHashov]

It is a common practice that exposed functions works with Int, not CInt/CSize because they would be more usable. Is it feasible to rewrite all unsafe functions with accordance to this rule?

[lpeterse]

Mhh, open for discussion.

The ByteString library has useAsCStringLen where CStringLen is an alias for (Ptr CChar, CSize). I thought it's not too unusual that one rather has aCSizethan anInt` when dealing with pointers and having allocated the buffer elsewhere.

useAsCStringLen :: ByteString -> (CStringLen -> IO a) -> IO a

[VyacheslavHashov]

As for example, allocating functions in Foreign.ForeignPtr work with Ints. But I have taken your point. If a function already has Ptr in the signature than changing CInt to Int gives no appreciable benefit.

[lpeterse]

One more point for future readers:

CSize is Word64 whereas an Int is only guaranteed to be defined up to 2^29.