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{-# LANGUAGE ExistentialQuantification, DeriveDataTypeable, StandaloneDeriving #-}
module Phi.Phi ( Phi
, Message
, DefaultMessage(..)
, fromMessage
, initPhi
, dupPhi
, sendMessage
, receiveMessage
, messageAvailable
) where
import Control.Concurrent.STM
import Control.Monad
import Control.Monad.IO.Class
import Data.Typeable
data Phi = Phi !(TChan Message)
data Message = forall a. (Typeable a, Show a) => Message a
deriving instance Show Message
data DefaultMessage = Repaint | ResetBackground | Shutdown | HoldShutdown | ReleaseShutdown deriving (Typeable, Show)
fromMessage :: (Typeable a, Show a) => Message -> Maybe a
fromMessage (Message m) = cast m
initPhi :: MonadIO m => m Phi
initPhi = liftM Phi $ liftIO $ atomically newTChan
dupPhi :: MonadIO m => Phi -> m Phi
dupPhi (Phi chan) = liftM Phi $ liftIO $ atomically $ dupTChan chan
sendMessage :: (MonadIO m, Typeable a, Show a) => Phi -> a -> m ()
sendMessage (Phi chan) = liftIO . atomically . writeTChan chan . Message
receiveMessage :: MonadIO m => Phi -> m Message
receiveMessage (Phi chan) = liftIO $ atomically $ readTChan chan
messageAvailable :: MonadIO m => Phi -> m Bool
messageAvailable (Phi chan) = liftIO $ liftM not $ atomically $ isEmptyTChan chan
|
