Effectful.Resource

Resource management via MonadResource.

Effect

data Resource :: Effect

Provide the ability to use the MonadResource instance of Eff.

Instances

newtype StaticRep Resource

Defined in Effectful.Resource

newtype StaticRep Resource = Resource InternalState

type DispatchOf Resource

Defined in Effectful.Resource

type DispatchOf Resource = 'Static 'WithSideEffects

Handlers

runResource :: IOE :> es => Eff (Resource ': es) a -> Eff es a

Run the resource effect.

Registering and releasing resources

allocate

Arguments

:: MonadResource m

=> IO a

allocate

-> (a -> IO ())

free resource

-> m (ReleaseKey, a)

Perform some allocation, and automatically register a cleanup action.

This is almost identical to calling the allocation and then registering the release action, but this properly handles masking of asynchronous exceptions.

Since 0.3.0

allocate_

Arguments

:: MonadResource m

=> IO a

allocate

-> IO ()

free resource

-> m ReleaseKey

Perform some allocation where the return value is not required, and automatically register a cleanup action.

allocate_ is to allocate as bracket_ is to bracket

This is almost identical to calling the allocation and then registering the release action, but this properly handles masking of asynchronous exceptions.

Since: resourcet-1.2.4

register :: MonadResource m => IO () -> m ReleaseKey

Register some action that will be called precisely once, either when runResourceT is called, or when the ReleaseKey is passed to release.

Since 0.3.0

release :: MonadIO m => ReleaseKey -> m ()

Call a release action early, and deregister it from the list of cleanup actions to be performed.

Since 0.3.0

unprotect :: MonadIO m => ReleaseKey -> m (Maybe (IO ()))

Unprotect resource from cleanup actions; this allows you to send resource into another resourcet process and reregister it there. It returns a release action that should be run in order to clean resource or Nothing in case if resource is already freed.

Since 0.4.5

Internal state

type InternalState = IORef ReleaseMap

The internal state held by a ResourceT transformer.

Since 0.4.6

getInternalState :: Resource :> es => Eff es InternalState

Get the InternalState of the current Resource effect.

runInternalState :: IOE :> es => InternalState -> Eff (Resource ': es) a -> Eff es a

Run the Resource effect with existing InternalState.

Note: the InternalState will not be closed at the end.

createInternalState :: MonadIO m => m InternalState

Create a new internal state. This state must be closed with closeInternalState. It is your responsibility to ensure exception safety. Caveat emptor!

Since 0.4.9

closeInternalState :: MonadIO m => InternalState -> m ()

Close an internal state created by createInternalState.

Since 0.4.9

Orphan instances

(IOE :> es, Resource :> es) => MonadResource (Eff es)

Methods

liftResourceT :: ResourceT IO a -> Eff es a