Excerpts from Thomas DuBuisson's message of Mon Aug 24 21:34:01 +0300 2009:
I Object! Code that uses addresses _might_ be very specific to IPv4 or IPv6 - such code should be able to restrict itself to the proper category of addresses, headers etc without resorting to partial functions. I propose a solution akin to:
class Address a where ... instance Address IPv4 instance Address IPv6
Also we could have data ConnectOptions t where ... instance Address t => Address (ConnectOptions t) where ...
I understand the issue, but it would be a shame if a new network package failed to have functional Address parsing - its just such a basic thing. I suppose this gives even more weight to a dual package solution.
IP-address parsing does not need Parsec. It is really quite simple. Which type system extensions can we use? e.g. GADTs are attractive but not supported by Hugs... Here is a little bit of formulation for a possible high-level API. Connections
type HostName = String type Port = Word16
data IPv4 = IPv4 HostName Port data IPv6 = IPv6 HostName Port data IP = IP HostName Port data Unix = Unix FilePath data AddressOptions t where ...
data Stream data Packet
class Address t where connectStream :: t -> IO (Socket Stream) connectPacket :: t -> IO (Socket Packet)
instance Connect IPv4 where ... instance Connect IPv6 where ... instance Connect IP where ... instance Connect (AddressOptions t) where ... instance Connect Unix where ...
withStream :: Address a => a -> (Socket Stream -> IO a) -> IO a withPacket :: Address a => a -> (Socket Packet -> IO a) -> IO a
socketToHandle :: Socket Stream -> IO Handle
Sending and receiving
-- | Send a bytestring send :: Socket t -> L.ByteString -> IO () -- | Receive a bytestring with a maximum length recv :: Socket t -> Int -> IO L.ByteString -- | Receive from -- FIXME SomeAddress here is a kludge, what would be better? recvFrom :: Socket t -> Int -> IO (L.ByteString, SomeAddress) close :: Socket t -> IO () sendTo :: Address a => Socket Packet -> a -> L.ByteString -> IO ()
Server API
data ServerOptions t where ... -- FIXME server :: ServerOptions t -> (Socket t -> SomeAddress -> IO ()) -> IO Foobar
Miscellaneous highlevel api
sleepForever :: IO () getCurrentHost :: IO HostName nameToNumeric :: Address a => a -> IO a numericToName :: Address a => a -> IO a
- Taru Karttunen