On Sun, 2006-11-12 at 10:49 -0800, Donn Cave wrote:
How do people like to set up their foreign I/O functions to return ByteStrings? I was a little stumped over this yesterday evening, while trying to write ` recv :: Socket -> Int -> Int -> ByteString '
Doc says `Byte vectors are encoded as strict Word8 arrays of bytes, held in a ForeignPtr, and can be passed between C and Haskell with little effort.' Which sounds perfect - I'm always up for `little effort'!
CString doesn't seem like the right thing for socket results, because the data shouldn't be NUL-terminated, and I might want to realloc when the returned data doesn't fill the buffer. I don't see any other Ptr-related function or constructor in the documentation - am I missing something there?
packCStringLen :: CStringLen -> ByteString (type CStringLen = (Ptr CChar, Int)) http://www.haskell.org/ghc/docs/latest/html/libraries/base/Data-ByteString.h... So if you know the length and the pointer to the beginning of the buffer then it's just packCStringLen (ptr, len) Of course you're not allowed to change the buffer after this, if you are using a mutable buffer then you'll have to make a copy: copyCStringLen :: CStringLen -> IO ByteString Duncan