\ignore{ 
> module Control.Concurrent.SimpleSession.TChan (
>   TChan, newTChan, writeTChan, readTChan
> ) where
> 
> import Control.Concurrent.Chan.Synchronous
} A |TChan a| is a monomorphic, synchronous channel that can transmit values of type |a|. 
> type TChan a
\ignore{ 
>   = Chan a
> 
> newTChan = newChan
> 
> writeTChan = writeChan
> 
> readTChan = readChan
} |TChan| has three operations: 
> newTChan   :: IO (TChan a)
> writeTChan :: TChan a -> a -> IO ()
> readTChan  :: TChan a -> IO a