channel.hs

来自「Cores are generated from Confluence a mo」· HS 代码 · 共 33 行

-- | A channel is a uni-directional communication link between two asynchronous processes.
module Language.Atom.Common.Channel
  ( Channel
  , channel
  , writeChannel
  , readChannel
  ) where

import Language.Atom

-- | A channel is a uni-directional communication link that ensures one read for every write.
data Channel a = Channel a (Var Bool)

-- | Creates a new channel, with a given name and data.
channel :: Name -> a -> System (Channel a)
channel name a = do
  hasData <- bool name False
  return $ Channel a hasData

-- | Write data to a 'Channel'.  A write will only suceed if the 'Channel' is empty.
writeChannel :: Channel a -> Action ()
writeChannel (Channel _ hasData) = do
  when $ inv $ value hasData
  hasData <== true
  
-- | Read data from a 'Channel'.  A read will only suceed if the 'Channel' has data to be read.
readChannel :: Channel a -> Action a
readChannel (Channel a hasData) = do
  when $ value hasData
  hasData <== false
  return a