| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Control.Monad.Trans.Resource.Internal
Synopsis
- data InvalidAccess = InvalidAccess { }
-
class
MonadIO
m =>
MonadResource
m
where
- liftResourceT :: ResourceT IO a -> m a
- data ReleaseKey = ReleaseKey !( IORef ReleaseMap ) ! Int
-
data
ReleaseMap
- = ReleaseMap !NextKey !RefCount !( IntMap ( ReleaseType -> IO ()))
- | ReleaseMapClosed
- type ResIO = ResourceT IO
-
newtype
ResourceT
m a =
ResourceT
{
- unResourceT :: IORef ReleaseMap -> m a
- stateAlloc :: IORef ReleaseMap -> IO ()
- stateCleanup :: ReleaseType -> IORef ReleaseMap -> IO ()
- transResourceT :: (m a -> n b) -> ResourceT m a -> ResourceT n b
- register' :: IORef ReleaseMap -> IO () -> IO ReleaseKey
- registerType :: IORef ReleaseMap -> ( ReleaseType -> IO ()) -> IO ReleaseKey
- data ResourceCleanupException = ResourceCleanupException { }
- stateCleanupChecked :: Maybe SomeException -> IORef ReleaseMap -> IO ()
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
Constructors
| InvalidAccess | |
|
Fields |
|
Instances
| Show InvalidAccess Source # | |
|
Defined in Control.Monad.Trans.Resource.Internal |
|
| Exception InvalidAccess Source # | |
|
Defined in Control.Monad.Trans.Resource.Internal Methods toException :: InvalidAccess -> SomeException Source # fromException :: SomeException -> Maybe InvalidAccess Source # |
|
class MonadIO m => MonadResource m where Source #
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
Methods
liftResourceT :: ResourceT IO a -> m a Source #
Lift a
ResourceT IO
action into the current
Monad
.
Since 0.4.0
Instances
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
Constructors
| ReleaseKey !( IORef ReleaseMap ) ! Int |
data ReleaseMap Source #
Constructors
| ReleaseMap !NextKey !RefCount !( IntMap ( ReleaseType -> IO ())) | |
| ReleaseMapClosed |
newtype ResourceT m a Source #
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
|
|
Instances
stateAlloc :: IORef ReleaseMap -> IO () Source #
stateCleanup :: ReleaseType -> IORef ReleaseMap -> IO () Source #
transResourceT :: (m a -> n b) -> ResourceT m a -> ResourceT n b Source #
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 Source #
registerType :: IORef ReleaseMap -> ( ReleaseType -> IO ()) -> IO ReleaseKey Source #
Since 1.1.2
data ResourceCleanupException Source #
Thrown when one or more cleanup functions themselves throw an exception during cleanup.
Since: 1.1.11
Constructors
| ResourceCleanupException | |
|
Fields
|
|
Instances
Arguments
| :: Maybe SomeException |
exception that killed the
|
| -> IORef ReleaseMap | |
| -> IO () |
Clean up a release map, but throw a
ResourceCleanupException
if
anything goes wrong in the cleanup handlers.
Since: 1.1.11