Streamly.Internal.Control.Concurrent

Please do not add any general routines in this. It should be renamed appropriately.

Documentation

type MonadAsync m = (MonadIO m, MonadBaseControl IO m, MonadThrow m)

A monad that can perform concurrent or parallel IO operations. Streams that can be composed concurrently require the underlying monad to be MonadAsync.

type MonadRunInIO m = (MonadIO m, MonadBaseControl IO m)

newtype RunInIO (m :: Type -> Type)

Constructors

RunInIO

Fields

• runInIO :: forall b. m b -> IO (StM m b)

askRunInIO :: MonadRunInIO m => m (RunInIO m)

When we run computations concurrently, we completely isolate the state of the concurrent computations from the parent computation. The invariant is that we should never be running two concurrent computations in the same thread without using the runInIO function. Also, we should never be running a concurrent computation in the parent thread, otherwise it may affect the state of the parent which is against the defined semantics of concurrent execution.

withRunInIO :: MonadRunInIO m => ((forall a. m a -> IO (StM m a)) -> IO (StM m b)) -> m b

withRunInIONoRestore :: MonadRunInIO m => ((forall a. m a -> IO (StM m a)) -> IO b) -> m b

restoreM :: MonadBaseControl b m => StM m a -> m a

Construct a m computation from the monadic state of m that is returned from a RunInBase function.

Instances should satisfy:

liftBaseWith (\runInBase -> runInBase m) >>= restoreM = m

restoreM is usually not implemented directly, but using defaultRestoreM.