content: {-# LANGUAGE TemplateHaskell, DeriveDataTypeable, DeriveGeneric #-}
  {-# OPTIONS_GHC -Wall #-}
  import Control.Distributed.Process hiding (Message)
  import Control.Distributed.Process.Closure
  
  import DistribUtils
  
  import Text.Printf
  import Data.Binary
  import Data.Typeable
  import GHC.Generics (Generic)
  
  -- <<Message
  data Message = Ping ProcessId
               | Pong ProcessId
    deriving (Typeable, Generic)          -- <1>
  
  instance Binary Message                 -- <2>
  -- >>
  
  -- <<pingServer
  pingServer :: Process ()
  pingServer = do
    Ping from <- expect                              -- <1>
    say $ printf "ping received from %s" (show from) -- <2>
    mypid <- getSelfPid                              -- <3>
    send from (Pong mypid)                           -- <4>
  -- >>
  
  -- <<remotable
  remotable ['pingServer]
  -- >>
  
  -- <<master
  master :: Process ()
  master = do
    node <- getSelfNode                               -- <1>
  
    say $ printf "spawning on %s" (show node)
    pid <- spawn node $(mkStaticClosure 'pingServer)  -- <2>
  
    mypid <- getSelfPid                               -- <3>
    say $ printf "sending ping to %s" (show pid)
    send pid (Ping mypid)                             -- <4>
  
    Pong _ <- expect                                  -- <5>
    say "pong."
  
    terminate                                         -- <6>
  -- >>
  
  -- <<main
  main :: IO ()
  main = distribMain (\_ -> master) Main.__remoteTable
  -- >>
  