Google Protobuf Example in Haskell

HsProtobufEx.hs

{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE DataKinds #-}

import Data.Int
import Data.ProtocolBuffers
import Data.Text
import GHC.Generics (Generic)
import GHC.TypeLits
import Data.Serialize
import Data.Monoid
import Data.Hex

data Foo = Foo
   {
     field1 :: Required 1 (Value Int64) -- ^ The last field with tag = 1
   , field2 :: Optional 2 (Value Text) -- ^ The last field with tag = 2
   , field3 :: Repeated 3 (Value Bool) -- ^ All fields with tag = 3, ordering is preserved
   } deriving (Generic, Show)

instance Encode Foo
instance Decode Foo

main = do
  let msg = Foo{field1 = putField 42, field2 = mempty, field3 = putField [True, False]}
  let encoded = fmap hex runPut $ encodeMessage msg
  print encoded