Hello.hs

{-# LANGUAGE BangPatterns, DeriveDataTypeable, FlexibleInstances, MultiParamTypeClasses #-}
module Proto.King.Hello (Hello(..)) where
import Prelude ((+), (/))
import qualified Prelude as Prelude'
import qualified Data.Typeable as Prelude'
import qualified Data.Data as Prelude'
import qualified Text.ProtocolBuffers.Header as P'
import qualified Proto.King.NodeDescription as King (NodeDescription)
 
data Hello = Hello{hNodeDesc :: !King.NodeDescription}
           deriving (Prelude'.Show, Prelude'.Eq, Prelude'.Ord, Prelude'.Typeable, Prelude'.Data)
 
instance P'.Mergeable Hello where
  mergeAppend (Hello x'1) (Hello y'1) = Hello (P'.mergeAppend x'1 y'1)
 
instance P'.Default Hello where
  defaultValue = Hello P'.defaultValue
 
instance P'.Wire Hello where
  wireSize ft' self'@(Hello x'1)
   = case ft' of
       10 -> calc'Size
       11 -> P'.prependMessageSize calc'Size
       _ -> P'.wireSizeErr ft' self'
    where
        calc'Size = (P'.wireSizeReq 1 11 x'1)
  wirePut ft' self'@(Hello x'1)
   = case ft' of
       10 -> put'Fields
       11 -> do
               P'.putSize (P'.wireSize 10 self')
               put'Fields
       _ -> P'.wirePutErr ft' self'
    where
        put'Fields
         = do
             P'.wirePutReq 10 11 x'1
  wireGet ft'
   = case ft' of
       10 -> P'.getBareMessageWith update'Self
       11 -> P'.getMessageWith update'Self
       _ -> P'.wireGetErr ft'
    where
        update'Self wire'Tag old'Self
         = case wire'Tag of
             10 -> Prelude'.fmap (\ !new'Field -> old'Self{hNodeDesc = P'.mergeAppend (hNodeDesc old'Self) (new'Field)})
                    (P'.wireGet 11)
             _ -> let (field'Number, wire'Type) = P'.splitWireTag wire'Tag in P'.unknown field'Number wire'Type old'Self
 
instance P'.MessageAPI msg' (msg' -> Hello) Hello where
  getVal m' f' = f' m'
 
instance P'.GPB Hello
 
instance P'.ReflectDescriptor Hello where
  getMessageInfo _ = P'.GetMessageInfo (P'.fromDistinctAscList [10]) (P'.fromDistinctAscList [10])
  reflectDescriptorInfo _
   = Prelude'.read
      "DescriptorInfo {descName = ProtoName {protobufName = FIName \".King.Hello\", haskellPrefix = [MName \"Proto\"], parentModule = [MName \"King\"], baseName = MName \"Hello\"}, descFilePath = [\"Proto\",\"King\",\"Hello.hs\"], isGroup = False, fields = fromList [FieldInfo {fieldName = ProtoFName {protobufName' = FIName \".King.Hello.hNodeDesc\", haskellPrefix' = [MName \"Proto\"], parentModule' = [MName \"King\",MName \"Hello\"], baseName' = FName \"hNodeDesc\"}, fieldNumber = FieldId {getFieldId = 1}, wireTag = WireTag {getWireTag = 10}, packedTag = Nothing, wireTagLength = 1, isPacked = False, isRequired = True, canRepeat = False, mightPack = False, typeCode = FieldType {getFieldType = 11}, typeName = Just (ProtoName {protobufName = FIName \".King.NodeDescription\", haskellPrefix = [MName \"Proto\"], parentModule = [MName \"King\"], baseName = MName \"NodeDescription\"}), hsRawDefault = Nothing, hsDefault = Nothing}], keys = fromList [], extRanges = [], knownKeys = fromList [], storeUnknown = False, lazyFields = False}"

Main.hs

import Messages

main :: IO ()
main = do
  input <- newChan
  receiver input
  forver $ do
    msg <- readChan input
    putStrLn $ show msg

Messages.hs

class Message a where
  pack :: a -> ByteString
  unpack :: ByteString -> Maybe a

data HelloMsg = HelloMsg deriving Show
instance Message HelloMsg -- ... using protobuf

data PingMsg = PingMsg deriving Show
instance Message PingMsg -- ... using protobuf

data PongMsg = PongMsg deriving Show
instance Message PongMsg -- ... using protobuf
-- and more 50 another...

data MsgType = Hello | Ping | Pong -- | and more 50 another ...
data CommonMsg a = CommonMsg MsgType a deriving Show

instance (Message a) => CommonMsg a where
  pack (CommonMsg type msg) = concat [packType type, pack msg]
  unpack bin = let (type, rest) = unpackType bin in CommonMsg type <$> unpack rest

receiver :: Chan (CommonMsg a) -> IO ()
receiver out = void $ forkIO $ forever $ do
  msg <- unpack <$> getCommonMsgFromNet
  writeChan out