Safe Haskell | None |
---|
- data InvalidAccess = InvalidAccess {}
- class (MonadThrow m, MonadIO m, Applicative m, MonadBase IO m) => MonadResource m where
- liftResourceT :: ResourceT IO a -> m a
- data ReleaseKey = ReleaseKey !(IORef ReleaseMap) !Int
- data ReleaseMap
- = ReleaseMap !NextKey !RefCount !(IntMap (IO ()))
- | ReleaseMapClosed
- type ResIO a = ResourceT IO a
- newtype ResourceT m a = ResourceT {
- unResourceT :: IORef ReleaseMap -> m a
- stateAlloc :: IORef ReleaseMap -> IO ()
- stateCleanup :: IORef ReleaseMap -> IO ()
- transResourceT :: (m a -> n b) -> ResourceT m a -> ResourceT n b
- register' :: IORef ReleaseMap -> IO () -> IO ReleaseKey
Documentation
data InvalidAccess Source
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
class (MonadThrow m, MonadIO m, Applicative m, MonadBase IO m) => MonadResource m whereSource
A Monad
which allows for safe resource allocation. In theory, any monad
transformer stack included a ResourceT
can be an instance of
MonadResource
.
Note: runResourceT
has a requirement for a MonadBaseControl IO 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
liftResourceT :: ResourceT IO a -> m aSource
Lift a ResourceT IO
action into the current Monad
.
Since 0.4.0
MonadResource m => MonadResource (ListT m) | |
MonadResource m => MonadResource (MaybeT m) | |
MonadResource m => MonadResource (IdentityT m) | |
(MonadThrow m, MonadBase IO m, MonadIO m, Applicative m) => MonadResource (ResourceT m) | |
MonadResource m => MonadResource (ContT r m) | |
(Error e, MonadResource m) => MonadResource (ErrorT e m) | |
MonadResource m => MonadResource (ReaderT r m) | |
MonadResource m => MonadResource (StateT s m) | |
MonadResource m => MonadResource (StateT s m) | |
(Monoid w, MonadResource m) => MonadResource (WriterT w m) | |
(Monoid w, MonadResource m) => MonadResource (WriterT w m) | |
(Monoid w, MonadResource m) => MonadResource (RWST r w s m) | |
(Monoid w, MonadResource m) => MonadResource (RWST r w s m) |
data ReleaseKey Source
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
ReleaseKey !(IORef ReleaseMap) !Int |
data ReleaseMap Source
ReleaseMap !NextKey !RefCount !(IntMap (IO ())) | |
ReleaseMapClosed |
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
ResourceT | |
|
MFunctor ResourceT | Since 0.4.7 |
MMonad ResourceT | Since 0.4.7 |
MonadTrans ResourceT | |
MonadTransControl ResourceT | |
MonadRWS r w s m => MonadRWS r w s (ResourceT m) | |
MonadBase b m => MonadBase b (ResourceT m) | |
MonadBaseControl b m => MonadBaseControl b (ResourceT m) | |
MonadError e m => MonadError e (ResourceT m) | |
MonadReader r m => MonadReader r (ResourceT m) | |
MonadState s m => MonadState s (ResourceT m) | |
MonadWriter w m => MonadWriter w (ResourceT m) | |
Monad m => Monad (ResourceT m) | |
Functor m => Functor (ResourceT m) | |
Typeable1 m => Typeable1 (ResourceT m) | |
Applicative m => Applicative (ResourceT m) | |
MonadThrow m => MonadThrow (ResourceT m) | |
MonadIO m => MonadIO (ResourceT m) | |
MonadCont m => MonadCont (ResourceT m) | |
(MonadThrow m, MonadBase IO m, MonadIO m, Applicative m) => MonadResource (ResourceT m) |
stateAlloc :: IORef ReleaseMap -> IO ()Source
stateCleanup :: IORef ReleaseMap -> IO ()Source
transResourceT :: (m a -> n b) -> ResourceT m a -> ResourceT n bSource
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 ReleaseKeySource