Allow Transport inbound/outbout types to vary.

1 files changed, 11 insertions, 9 deletions

diff --git a/src/Network/QueryResponse.hs b/src/Network/QueryResponse.hs
index 6df9ac5a..fdfbdbae 100644
--- a/src/Network/QueryResponse.hs
+++ b/src/Network/QueryResponse.hs
@@ -40,18 +40,20 @@ import System.Timeout
 import DPut
 
 -- | Three methods are required to implement a datagram based query\/response protocol.
-data Transport err addr x = Transport
+data TransportA err addr x y = Transport
     { -- | Blocks until an inbound packet is available. Returns 'Nothing' when
       -- no more packets are expected due to a shutdown or close event.
       -- Otherwise, the packet will be parsed as type /x/ and an origin address
       -- /addr/.  Parse failure is indicated by the type 'err'.
       awaitMessage :: forall a. (Maybe (Either err (x, addr)) -> IO a) -> IO a
-      -- | Send an /x/ packet to the given destination /addr/.
-    , sendMessage :: addr -> x -> IO ()
+      -- | Send an /y/ packet to the given destination /addr/.
+    , sendMessage :: addr -> y -> IO ()
       -- | Shutdown and clean up any state related to this 'Transport'.
     , closeTransport :: IO ()
     }
 
+type Transport err addr x = TransportA err addr x x
+
 -- | This function modifies a 'Transport' to use higher-level addresses and
 -- packet representations.  It could be used to change UDP 'ByteString's into
 -- bencoded syntax trees or to add an encryption layer in which addresses have
@@ -60,12 +62,12 @@ layerTransportM ::
         (x -> addr -> IO (Either err (x', addr')))
         -- ^ Function that attempts to transform a low-level address/packet
         -- pair into a higher level representation.
-        -> (x' -> addr' -> IO (x, addr))
+        -> (y' -> addr' -> IO (y, addr))
         -- ^ Function to encode a high-level address/packet into a lower level
         -- representation.
-        -> Transport err addr x
+        -> TransportA err addr x y
         -- ^ The low-level transport to be transformed.
-        -> Transport err addr' x'
+        -> TransportA err addr' x' y'
 layerTransportM parse encode tr =
     tr { awaitMessage = \kont ->
                 awaitMessage tr $ \m -> mapM (mapM $ uncurry parse) m >>= kont . fmap join
@@ -83,12 +85,12 @@ layerTransport ::
         (x -> addr -> Either err (x', addr'))
         -- ^ Function that attempts to transform a low-level address/packet
         -- pair into a higher level representation.
-        -> (x' -> addr' -> (x, addr))
+        -> (y' -> addr' -> (y, addr))
         -- ^ Function to encode a high-level address/packet into a lower level
         -- representation.
-        -> Transport err addr x
+        -> TransportA err addr x y
         -- ^ The low-level transport to be transformed.
-        -> Transport err addr' x'
+        -> TransportA err addr' x' y'
 layerTransport parse encode tr =
     layerTransportM (\x addr -> return $ parse x addr)
                     (\x' addr' -> return $ encode x' addr')