-- Communicating Haskell Processes.
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module Control.Concurrent.CHPSpec.Channels.Base where

import Control.Arrow ((&&&))
import Control.Monad
import Control.Monad.Trans
import Data.Typeable

import Control.Concurrent.CHPSpec.Base
import Control.Concurrent.CHPSpec.CSP
import Control.Concurrent.CHPSpec.Spec

newtype Chanin a = Chanin (STMChannel a) deriving (Eq, Typeable)

newtype Chanout a = Chanout (STMChannel a) deriving (Eq, Typeable)

newtype STMChannel a = STMChan EventId
  deriving (Eq, Typeable)

data Chan r w a = Chan {
  -- | Gets the channel's identifier.  Useful if you need to be able to identify
  -- a channel in the trace later on.
  getChannelIdentifier :: EventId,
  reader :: r a,
  writer :: w a}

instance Poisonable (Chanin a) where
  poison (Chanin _) = return ()
  checkForPoison (Chanin _) = return ()

instance Poisonable (Chanout a) where
  poison (Chanout _) = return ()
  checkForPoison (Chanout _) = return ()

stmChannel :: MonadCHP m => m (EventId, STMChannel a)
stmChannel = liftM (id &&& STMChan) $ liftCHP $ lift newEvent