Control.Effect.Resource

Documentation

data Resource m k

Constructors

Resource (m resource) (resource -> m any) (resource -> m output) (output -> k)

OnError (m resource) (resource -> m any) (resource -> m output) (output -> k)

Instances

Effect Resource

Defined in Control.Effect.Resource

Methods

handle :: Functor f => f () -> (forall x. f (m x) -> n (f x)) -> Resource m (m a) -> Resource n (n (f a))

HFunctor Resource

Defined in Control.Effect.Resource

Methods

fmap' :: (a -> b) -> Resource m a -> Resource m b

hmap :: (forall x. m x -> n x) -> Resource m a -> Resource n a

Functor (Resource m)

Defined in Control.Effect.Resource

Methods

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

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

(Carrier sig m, MonadIO m) => Carrier (Resource :+: sig) (ResourceC m)

Defined in Control.Effect.Resource

Methods

ret :: a -> ResourceC m a

eff :: (Resource :+: sig) (ResourceC m) (ResourceC m a) -> ResourceC m a

bracket

Arguments

:: (Member Resource sig, Carrier sig m)

=> m resource

computation to run first ("acquire resource")

-> (resource -> m any)

computation to run last ("release resource")

-> (resource -> m a)

computation to run in-between

-> m a

Provides a safe idiom to acquire and release resources safely.

When acquiring and operating on a resource (such as opening and reading file handle with openFile or writing to a blob of memory with malloc), any exception thrown during the operation may mean that the resource is not properly released. bracket acquire release op ensures that release is run on the value returned from acquire even if op throws an exception.

bracket is safe in the presence of asynchronous exceptions.

bracketOnError

Arguments

:: (Member Resource sig, Carrier sig m)

=> m resource

computation to run first ("acquire resource")

-> (resource -> m any)

computation to run last ("release resource")

-> (resource -> m a)

computation to run in-between

-> m a

Like bracket, but only performs the final action if there was an exception raised by the in-between computation.

finally

Arguments

:: (Member Resource sig, Carrier sig m, Applicative m)

=> m a

computation to run first

-> m b

computation to run afterward (even if an exception was raised)

-> m a

Like bracket, but for the simple case of one computation to run afterward.

onException

Arguments

:: (Member Resource sig, Carrier sig m, Applicative m)

=> m a

computation to run first

-> m b

computation to run afterward if an exception was raised

-> m a

Like bracketOnError, but for the simple case of one computation to run afterward.

runResource :: (Carrier sig m, MonadIO m) => (forall x. m x -> IO x) -> Eff (ResourceC m) a -> m a

newtype ResourceC m a

Constructors

ResourceC ((forall x. m x -> IO x) -> m a)

Instances

(Carrier sig m, MonadIO m) => Carrier (Resource :+: sig) (ResourceC m)

Defined in Control.Effect.Resource

Methods

ret :: a -> ResourceC m a

eff :: (Resource :+: sig) (ResourceC m) (ResourceC m a) -> ResourceC m a