Copyright | (c) 2017 Composewell Technologies |
---|---|

License | BSD-3-Clause |

Maintainer | streamly@composewell.com |

Stability | experimental |

Portability | GHC |

Safe Haskell | Safe-Inferred |

Language | Haskell2010 |

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

## Synopsis

- type MonadAsync m = (MonadIO m, MonadBaseControl IO m, MonadThrow m)
- type MonadRunInIO m = (MonadIO m, MonadBaseControl IO m)
- newtype RunInIO (m :: Type -> TYPE LiftedRep) = RunInIO {}
- askRunInIO :: MonadRunInIO m => m (RunInIO m)
- 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

# Documentation

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

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) Source #

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

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 Source #

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

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

is usually not implemented directly, but using
`restoreM`

.`defaultRestoreM`