{-# LANGUAGE ExistentialQuantification, DeriveDataTypeable, StandaloneDeriving #-}

module Phi.Phi ( Phi
               , Message
               , DefaultMessage(..)
               , fromMessage
               , initPhi
               , sendMessage
               , receiveMessage
               ) where

import Control.Concurrent.Chan
import Control.Monad
import Data.Typeable

data Phi = Phi (Chan Message)

data Message = forall a. (Typeable a, Show a) => Message a
deriving instance Show Message

data DefaultMessage = Repaint deriving (Typeable, Show)

fromMessage :: (Typeable a, Show a) => Message -> Maybe a
fromMessage (Message m) = cast m

initPhi :: IO Phi
initPhi = liftM Phi newChan

sendMessage :: (Typeable a, Show a) => Phi -> a -> IO ()
sendMessage (Phi chan) = writeChan chan . Message

receiveMessage :: Phi -> IO Message
receiveMessage (Phi chan) = readChan chan