Control.Monad.Trans.Resource.Internal

Documentation

data InvalidAccess

Indicates either an error in the library, or misuse of it (e.g., a ResourceT's state is accessed after being released).

Since 0.3.0

Constructors

InvalidAccess

Fields

• functionName :: String

Instances

Show InvalidAccess

Methods

showsPrec :: Int -> InvalidAccess -> ShowS

show :: InvalidAccess -> String

showList :: [InvalidAccess] -> ShowS

Exception InvalidAccess

Methods

toException :: InvalidAccess -> SomeException

fromException :: SomeException -> Maybe InvalidAccess

displayException :: InvalidAccess -> String

class MonadIO m => MonadResource m where

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

Methods

liftResourceT :: ResourceT IO a -> m a

Lift a ResourceT IO action into the current Monad.

Since 0.4.0

Instances

MonadResource m => MonadResource (ListT m)

Methods

liftResourceT :: ResourceT IO a -> ListT m a

MonadResource m => MonadResource (MaybeT m)

Methods

liftResourceT :: ResourceT IO a -> MaybeT m a

MonadIO m => MonadResource (ResourceT m)

Methods

liftResourceT :: ResourceT IO a -> ResourceT m a

MonadResource m => MonadResource (ExceptT e m)

Methods

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

MonadResource m => MonadResource (StateT s m)

Methods

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

MonadResource m => MonadResource (StateT s m)

Methods

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

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

Methods

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

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

Methods

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

MonadResource m => MonadResource (IdentityT * m)

Methods

liftResourceT :: ResourceT IO a -> IdentityT * m a

MonadResource m => MonadResource (ContT * r m)

Methods

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

MonadResource m => MonadResource (ReaderT * r m)

Methods

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

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

Methods

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

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

Methods

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

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

Constructors

ReleaseKey !(IORef ReleaseMap) !Int

data ReleaseMap

Constructors

ReleaseMap !NextKey !RefCount !(IntMap (ReleaseType -> IO ()))

ReleaseMapClosed

type ResIO = ResourceT IO

Convenient alias for ResourceT IO.

newtype 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

Constructors

ResourceT

Fields

• unResourceT :: IORef ReleaseMap -> m a

Instances

MonadTrans ResourceT

Methods

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

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

MonadWriter w m => MonadWriter w (ResourceT m)

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)

Methods

get :: ResourceT m s

put :: s -> ResourceT m ()

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

MonadReader r m => MonadReader r (ResourceT m)

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)

Methods

throwError :: e -> ResourceT m a

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

Monad m => Monad (ResourceT m)

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)

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

Methods

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

Applicative m => Applicative (ResourceT m)

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)

Methods

liftIO :: IO a -> ResourceT m a

Alternative m => Alternative (ResourceT m)

Since 1.1.5

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

Methods

mzero :: ResourceT m a

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

MonadThrow m => MonadThrow (ResourceT m)

Methods

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

MonadCatch m => MonadCatch (ResourceT m)

Methods

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

MonadMask m => MonadMask (ResourceT m)

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

MonadCont m => MonadCont (ResourceT m)

Methods

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

PrimMonad m => PrimMonad (ResourceT m)

Associated Types

type PrimState (ResourceT m :: * -> *) :: *

Methods

primitive :: (State# (PrimState (ResourceT m)) -> (#TupleRep [RuntimeRep], LiftedRep, State# (PrimState (ResourceT m)), a#)) -> ResourceT m a

MonadUnliftIO m => MonadUnliftIO (ResourceT m)

Since: 1.1.10

Methods

askUnliftIO :: ResourceT m (UnliftIO (ResourceT m))

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

MonadIO m => MonadResource (ResourceT m)

Methods

liftResourceT :: ResourceT IO a -> ResourceT m a

type PrimState (ResourceT m)

type PrimState (ResourceT m) = PrimState m

stateAlloc :: IORef ReleaseMap -> IO ()

stateCleanup :: ReleaseType -> IORef ReleaseMap -> IO ()

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

Transform the monad a ResourceT lives in. This is most often used to strip or add new transformers to a stack, e.g. to run a ReaderT.

Note that this function is a slight generalization of hoist.

Since 0.3.0

register' :: IORef ReleaseMap -> IO () -> IO ReleaseKey

registerType :: IORef ReleaseMap -> (ReleaseType -> IO ()) -> IO ReleaseKey

Since 1.1.2

data ResourceCleanupException

Thrown when one or more cleanup functions themselves throw an exception during cleanup.

Since: 1.1.11

Constructors

ResourceCleanupException

Fields

• rceOriginalException :: !(Maybe SomeException)

  If the ResourceT block exited due to an exception, this is that exception.

  Since: 1.1.11

• rceFirstCleanupException :: !SomeException

  The first cleanup exception. We keep this separate from rceOtherCleanupExceptions to prove that there's at least one (i.e., a non-empty list).

  Since: 1.1.11

• rceOtherCleanupExceptions :: ![SomeException]

  All other exceptions in cleanups.

  Since: 1.1.11

Instances

Show ResourceCleanupException

Methods

showsPrec :: Int -> ResourceCleanupException -> ShowS

show :: ResourceCleanupException -> String

showList :: [ResourceCleanupException] -> ShowS

Exception ResourceCleanupException

Methods

toException :: ResourceCleanupException -> SomeException

fromException :: SomeException -> Maybe ResourceCleanupException

displayException :: ResourceCleanupException -> String

stateCleanupChecked

Arguments

:: Maybe SomeException

exception that killed the ResourceT, if present

-> IORef ReleaseMap

-> IO ()

Clean up a release map, but throw a ResourceCleanupException if anything goes wrong in the cleanup handlers.

Since: 1.1.11