UnliftIO.Resource

Unlifted Control.Monad.Trans.Resource.

Since: 1.1.10

UnliftIO variants

runResourceT :: MonadUnliftIO m => ResourceT m a -> m a

Unlifted version of runResourceT.

Since: 1.1.10

liftResourceT :: MonadIO m => ResourceT IO a -> ResourceT m a

Lifted version of liftResourceT.

Since: 1.1.10

Reexports

data ResourceT m a

The Resource transformer. This transformer keeps track of all registered actions, and calls them upon exit (via runResourceT). Actions may be registered via register, or resources may be allocated atomically via allocate. allocate corresponds closely to bracket.

Releasing may be performed before exit via the release function. This is a highly recommended optimization, as it will ensure that scarce resources are freed early. Note that calling release will deregister the action, so that a release action will only ever be called once.

Since 0.3.0

Instances

MonadTrans ResourceT

Defined in Control.Monad.Trans.Resource.Internal

Methods

lift :: Monad m => m a -> ResourceT m a

MonadRWS r w s m => MonadRWS r w s (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

MonadWriter w m => MonadWriter w (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

writer :: (a, w) -> ResourceT m a

tell :: w -> ResourceT m ()

listen :: ResourceT m a -> ResourceT m (a, w)

pass :: ResourceT m (a, w -> w) -> ResourceT m a

MonadState s m => MonadState s (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

get :: ResourceT m s

put :: s -> ResourceT m ()

state :: (s -> (a, s)) -> ResourceT m a

MonadReader r m => MonadReader r (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

ask :: ResourceT m r

local :: (r -> r) -> ResourceT m a -> ResourceT m a

reader :: (r -> a) -> ResourceT m a

MonadError e m => MonadError e (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

throwError :: e -> ResourceT m a

catchError :: ResourceT m a -> (e -> ResourceT m a) -> ResourceT m a

Monad m => Monad (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

(>>=) :: ResourceT m a -> (a -> ResourceT m b) -> ResourceT m b

(>>) :: ResourceT m a -> ResourceT m b -> ResourceT m b

return :: a -> ResourceT m a

fail :: String -> ResourceT m a

Functor m => Functor (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

fmap :: (a -> b) -> ResourceT m a -> ResourceT m b

(<$) :: a -> ResourceT m b -> ResourceT m a

MonadFix m => MonadFix (ResourceT m)

Since: 1.1.8

Defined in Control.Monad.Trans.Resource.Internal

Methods

mfix :: (a -> ResourceT m a) -> ResourceT m a

MonadFail m => MonadFail (ResourceT m)

Since: 1.2.2

Defined in Control.Monad.Trans.Resource.Internal

Methods

fail :: String -> ResourceT m a

Applicative m => Applicative (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

pure :: a -> ResourceT m a

(<*>) :: ResourceT m (a -> b) -> ResourceT m a -> ResourceT m b

liftA2 :: (a -> b -> c) -> ResourceT m a -> ResourceT m b -> ResourceT m c

(*>) :: ResourceT m a -> ResourceT m b -> ResourceT m b

(<*) :: ResourceT m a -> ResourceT m b -> ResourceT m a

MonadIO m => MonadIO (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftIO :: IO a -> ResourceT m a

Alternative m => Alternative (ResourceT m)

Since 1.1.5

Defined in Control.Monad.Trans.Resource.Internal

Methods

empty :: ResourceT m a

(<|>) :: ResourceT m a -> ResourceT m a -> ResourceT m a

some :: ResourceT m a -> ResourceT m [a]

many :: ResourceT m a -> ResourceT m [a]

MonadPlus m => MonadPlus (ResourceT m)

Since 1.1.5

Defined in Control.Monad.Trans.Resource.Internal

Methods

mzero :: ResourceT m a

mplus :: ResourceT m a -> ResourceT m a -> ResourceT m a

MonadThrow m => MonadThrow (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

throwM :: Exception e => e -> ResourceT m a

MonadCatch m => MonadCatch (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

catch :: Exception e => ResourceT m a -> (e -> ResourceT m a) -> ResourceT m a

MonadMask m => MonadMask (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

mask :: ((forall a. ResourceT m a -> ResourceT m a) -> ResourceT m b) -> ResourceT m b

uninterruptibleMask :: ((forall a. ResourceT m a -> ResourceT m a) -> ResourceT m b) -> ResourceT m b

generalBracket :: ResourceT m a -> (a -> ExitCase b -> ResourceT m c) -> (a -> ResourceT m b) -> ResourceT m (b, c)

MonadCont m => MonadCont (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

callCC :: ((a -> ResourceT m b) -> ResourceT m a) -> ResourceT m a

PrimMonad m => PrimMonad (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Associated Types

type PrimState (ResourceT m) :: Type

Methods

primitive :: (State# (PrimState (ResourceT m)) -> (#State# (PrimState (ResourceT m)), a#)) -> ResourceT m a

MonadUnliftIO m => MonadUnliftIO (ResourceT m)

Since: 1.1.10

Defined in Control.Monad.Trans.Resource.Internal

Methods

withRunInIO :: ((forall a. ResourceT m a -> IO a) -> IO b) -> ResourceT m b

MonadIO m => MonadResource (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ResourceT m a

type PrimState (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

type PrimState (ResourceT m) = PrimState m

data ReleaseKey

A lookup key for a specific release action. This value is returned by register and allocate, and is passed to release.

Since 0.3.0

class MonadIO m => MonadResource m

A Monad which allows for safe resource allocation. In theory, any monad transformer stack which includes a ResourceT can be an instance of MonadResource.

Note: runResourceT has a requirement for a MonadUnliftIO m monad, which allows control operations to be lifted. A MonadResource does not have this requirement. This means that transformers such as ContT can be an instance of MonadResource. However, the ContT wrapper will need to be unwrapped before calling runResourceT.

Since 0.3.0

Minimal complete definition

liftResourceT

Instances

MonadResource m => MonadResource (MaybeT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> MaybeT m a

MonadResource m => MonadResource (ListT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ListT m a

MonadIO m => MonadResource (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ResourceT m a

MonadResource m => MonadResource (ExceptT e m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ExceptT e m a

MonadResource m => MonadResource (IdentityT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> IdentityT m a

MonadResource m => MonadResource (StateT s m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> StateT s m a

MonadResource m => MonadResource (StateT s m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> StateT s m a

(Monoid w, MonadResource m) => MonadResource (WriterT w m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> WriterT w m a

(Monoid w, MonadResource m) => MonadResource (WriterT w m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> WriterT w m a

MonadResource m => MonadResource (ContT r m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ContT r m a

MonadResource m => MonadResource (ReaderT r m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ReaderT r m a

(Monoid w, MonadResource m) => MonadResource (RWST r w s m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> RWST r w s m a

(Monoid w, MonadResource m) => MonadResource (RWST r w s m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> RWST r w s m a

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

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