Safe Haskell	Safe
Language	Haskell2010

Data.Acquire.Internal

Synopsis

newtype Acquire a = Acquire ((forall b. IO b -> IO b) -> IO (Allocated a))
data Allocated a = Allocated !a !(ReleaseType -> IO ())
with :: MonadUnliftIO m => Acquire a -> (a -> m b) -> m b
mkAcquire :: IO a -> (a -> IO ()) -> Acquire a
data ReleaseType
- = ReleaseEarly
- | ReleaseNormal
- | ReleaseException
mkAcquireType :: IO a -> (a -> ReleaseType -> IO ()) -> Acquire a

Documentation

newtype Acquire a Source #

A method for acquiring a scarce resource, providing the means of freeing it when no longer needed. This data type provides Functor/Applicative/Monad instances for composing different resources together. You can allocate these resources using either the bracket pattern (via with) or using ResourceT (via allocateAcquire).

This concept was originally introduced by Gabriel Gonzalez and described at: http://www.haskellforall.com/2013/06/the-resource-applicative.html. The implementation in this package is slightly different, due to taking a different approach to async exception safety.

Since: 1.1.0

Constructors

Acquire ((forall b. IO b -> IO b) -> IO (Allocated a))

Instances

Monad Acquire Source #
Instance details Defined in Data.Acquire.Internal Methods (>>=) :: Acquire a -> (a -> Acquire b) -> Acquire b # (>>) :: Acquire a -> Acquire b -> Acquire b # return :: a -> Acquire a # fail :: String -> Acquire a #
Functor Acquire Source #
Instance details Defined in Data.Acquire.Internal Methods fmap :: (a -> b) -> Acquire a -> Acquire b # (<$) :: a -> Acquire b -> Acquire a #
Applicative Acquire Source #
Instance details Defined in Data.Acquire.Internal Methods pure :: a -> Acquire a # (<>) :: Acquire (a -> b) -> Acquire a -> Acquire b # liftA2 :: (a -> b -> c) -> Acquire a -> Acquire b -> Acquire c # (>) :: Acquire a -> Acquire b -> Acquire b # (<*) :: Acquire a -> Acquire b -> Acquire a #
MonadIO Acquire Source #
Instance details Defined in Data.Acquire.Internal Methods liftIO :: IO a -> Acquire a #

data Allocated a Source #

Constructors

Allocated !a !(ReleaseType -> IO ())

with :: MonadUnliftIO m => Acquire a -> (a -> m b) -> m b Source #

Allocate the given resource and provide it to the provided function. The resource will be freed as soon as the inner block is exited, whether normally or via an exception. This function is similar in function to bracket.

Since: 1.1.0

mkAcquire Source #

Arguments

:: IO a	acquire the resource
-> (a -> IO ())	free the resource
-> Acquire a

Create an Acquire value using the given allocate and free functions.

Since: 1.1.0

data ReleaseType Source #

The way in which a release is called.

Since: 1.1.2

Constructors

ReleaseEarly
ReleaseNormal
ReleaseException

Instances

Bounded ReleaseType Source #
Instance details Defined in Data.Acquire.Internal Methods minBound :: ReleaseType # maxBound :: ReleaseType #
Enum ReleaseType Source #
Instance details Defined in Data.Acquire.Internal Methods succ :: ReleaseType -> ReleaseType # pred :: ReleaseType -> ReleaseType # toEnum :: Int -> ReleaseType # fromEnum :: ReleaseType -> Int # enumFrom :: ReleaseType -> [ReleaseType] # enumFromThen :: ReleaseType -> ReleaseType -> [ReleaseType] # enumFromTo :: ReleaseType -> ReleaseType -> [ReleaseType] # enumFromThenTo :: ReleaseType -> ReleaseType -> ReleaseType -> [ReleaseType] #
Eq ReleaseType Source #
Instance details Defined in Data.Acquire.Internal Methods (==) :: ReleaseType -> ReleaseType -> Bool # (/=) :: ReleaseType -> ReleaseType -> Bool #
Ord ReleaseType Source #
Instance details Defined in Data.Acquire.Internal Methods compare :: ReleaseType -> ReleaseType -> Ordering # (<) :: ReleaseType -> ReleaseType -> Bool # (<=) :: ReleaseType -> ReleaseType -> Bool # (>) :: ReleaseType -> ReleaseType -> Bool # (>=) :: ReleaseType -> ReleaseType -> Bool # max :: ReleaseType -> ReleaseType -> ReleaseType # min :: ReleaseType -> ReleaseType -> ReleaseType #
Read ReleaseType Source #
Instance details Defined in Data.Acquire.Internal Methods readsPrec :: Int -> ReadS ReleaseType # readList :: ReadS [ReleaseType] # readPrec :: ReadPrec ReleaseType # readListPrec :: ReadPrec [ReleaseType] #
Show ReleaseType Source #
Instance details Defined in Data.Acquire.Internal Methods showsPrec :: Int -> ReleaseType -> ShowS # show :: ReleaseType -> String # showList :: [ReleaseType] -> ShowS #

mkAcquireType Source #

Arguments

:: IO a	acquire the resource
-> (a -> ReleaseType -> IO ())	free the resource
-> Acquire a

Same as mkAcquire, but the cleanup function will be informed of how cleanup was initiated. This allows you to distinguish, for example, between normal and exceptional exits.

Since: 1.1.2