om-socket-0.11.0.3: examples/server.hs

{-# LANGUAGE DerivingStrategies #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE OverloadedStrings #-}

{-# OPTIONS_GHC -Wwarn #-}

module Main (main) where

import Conduit ((.|), awaitForever, runConduit)
import Control.Monad.Logger (runStdoutLoggingT)
import Control.Monad.Trans.Class (MonadTrans(lift))
import Data.Binary (Binary)
import OM.Socket (openServer)

{- | The requests accepted by the server. -}
newtype Request = EchoRequest String
  deriving newtype (Binary, Show)


{- | The response sent back to the client. -}
newtype Responsee = EchoResponse String
  deriving newtype (Binary, Show)


{- | Simple echo resposne server. -}
main :: IO ()
main = do
  {-
    Don't actually call server, because the "test" we are using to make
    sure this compiles will never finish running!
  -}
  -- server
  pure ()


server :: IO ()
server =
  runStdoutLoggingT . runConduit $
    pure ()
    .| openServer "localhost:9000" Nothing
    .| awaitForever (\(EchoRequest str, respond) ->
        {-
          You don't necessarily have to respond right away if you don't
          want to. You can cache the responder away in some state and
          get back to it at some later time if you like.
        -}
        lift $ respond (EchoResponse str)
    )