| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Prolude.Exception
Synopsis
- assert :: Bool -> a -> a
- class Typeable (a :: k)
- data SomeAsyncException = Exception e => SomeAsyncException e
- data IOException
- class (Typeable e, Show e) => Exception e where
- toException :: e -> SomeException
- fromException :: SomeException -> Maybe e
- displayException :: e -> String
- data SomeException = Exception e => SomeException e
- class Monad m => MonadThrow (m :: Type -> Type)
- handleIOError :: MonadCatch m => (IOError -> m a) -> m a -> m a
- catchIOError :: MonadCatch m => m a -> (IOError -> m a) -> m a
- uninterruptibleMask_ :: MonadMask m => m a -> m a
- mask_ :: MonadMask m => m a -> m a
- class MonadThrow m => MonadCatch (m :: Type -> Type)
- class MonadCatch m => MonadMask (m :: Type -> Type) where
- mask :: ((forall a. m a -> m a) -> m b) -> m b
- uninterruptibleMask :: ((forall a. m a -> m a) -> m b) -> m b
- generalBracket :: m a -> (a -> ExitCase b -> m c) -> (a -> m b) -> m (b, c)
- data Handler (m :: Type -> Type) a = Exception e => Handler (e -> m a)
- catchesAsync :: (MonadCatch m, MonadThrow m) => m a -> [Handler m a] -> m a
- catchesDeep :: (MonadCatch m, MonadThrow m, MonadIO m, NFData a) => m a -> [Handler m a] -> m a
- catches :: (MonadCatch m, MonadThrow m) => m a -> [Handler m a] -> m a
- isAsyncException :: Exception e => e -> Bool
- isSyncException :: Exception e => e -> Bool
- toAsyncException :: Exception e => e -> SomeException
- toSyncException :: Exception e => e -> SomeException
- bracketWithError :: MonadMask m => m a -> (Maybe SomeException -> a -> m b) -> (a -> m c) -> m c
- bracketOnError_ :: MonadMask m => m a -> m b -> m c -> m c
- bracketOnError :: MonadMask m => m a -> (a -> m b) -> (a -> m c) -> m c
- finally :: MonadMask m => m a -> m b -> m a
- bracket_ :: MonadMask m => m a -> m b -> m c -> m c
- bracket :: MonadMask m => m a -> (a -> m b) -> (a -> m c) -> m c
- withException :: (MonadMask m, Exception e) => m a -> (e -> m b) -> m a
- onException :: MonadMask m => m a -> m b -> m a
- tryJust :: (MonadCatch m, Exception e) => (e -> Maybe b) -> m a -> m (Either b a)
- tryAsync :: (MonadCatch m, Exception e) => m a -> m (Either e a)
- tryAnyDeep :: (MonadCatch m, MonadIO m, NFData a) => m a -> m (Either SomeException a)
- tryDeep :: (MonadCatch m, MonadIO m, Exception e, NFData a) => m a -> m (Either e a)
- tryAny :: MonadCatch m => m a -> m (Either SomeException a)
- tryIO :: MonadCatch m => m a -> m (Either IOException a)
- try :: (MonadCatch m, Exception e) => m a -> m (Either e a)
- handleJust :: (MonadCatch m, Exception e) => (e -> Maybe b) -> (b -> m a) -> m a -> m a
- handleAsync :: (MonadCatch m, Exception e) => (e -> m a) -> m a -> m a
- handleAnyDeep :: (MonadCatch m, MonadIO m, NFData a) => (SomeException -> m a) -> m a -> m a
- handleDeep :: (MonadCatch m, Exception e, MonadIO m, NFData a) => (e -> m a) -> m a -> m a
- handleAny :: MonadCatch m => (SomeException -> m a) -> m a -> m a
- handleIO :: MonadCatch m => (IOException -> m a) -> m a -> m a
- handle :: (MonadCatch m, Exception e) => (e -> m a) -> m a -> m a
- catchJust :: (MonadCatch m, Exception e) => (e -> Maybe b) -> m a -> (b -> m a) -> m a
- catchAsync :: (MonadCatch m, Exception e) => m a -> (e -> m a) -> m a
- catchAnyDeep :: (MonadCatch m, MonadIO m, NFData a) => m a -> (SomeException -> m a) -> m a
- catchDeep :: (MonadCatch m, MonadIO m, Exception e, NFData a) => m a -> (e -> m a) -> m a
- catchAny :: MonadCatch m => m a -> (SomeException -> m a) -> m a
- catch :: (MonadCatch m, Exception e) => m a -> (e -> m a) -> m a
- impureThrow :: Exception e => e -> a
- throwTo :: (Exception e, MonadIO m) => ThreadId -> e -> m ()
- throwString :: (MonadThrow m, HasCallStack) => String -> m a
- throwIO :: (MonadThrow m, Exception e) => e -> m a
- throw :: (MonadThrow m, Exception e) => e -> m a
- data StringException = StringException String CallStack
- data SyncExceptionWrapper = Exception e => SyncExceptionWrapper e
- data AsyncExceptionWrapper = Exception e => AsyncExceptionWrapper e
- data AsyncException
- catchIf :: (MonadCatch m, Exception e) => (e -> Bool) -> m a -> (e -> m a) -> m a
- unsafeEvaluate :: a -> IO a
- unsafeThrow :: Exception e => e -> a
Exception re-exports
If the first argument evaluates to True, then the result is the
second argument. Otherwise an AssertionFailed exception
is raised, containing a String with the source file and line number of the
call to assert.
Assertions can normally be turned on or off with a compiler flag
(for GHC, assertions are normally on unless optimisation is turned on
with -O or the -fignore-asserts
option is given). When assertions are turned off, the first
argument to assert is ignored, and the second argument is
returned as the result.
The class Typeable allows a concrete representation of a type to
be calculated.
Minimal complete definition
typeRep#
data SomeAsyncException #
Superclass for asynchronous exceptions.
Since: base-4.7.0.0
Constructors
| Exception e => SomeAsyncException e |
Instances
| Show SomeAsyncException | Since: base-4.7.0.0 |
Defined in GHC.IO.Exception Methods showsPrec :: Int -> SomeAsyncException -> ShowS # show :: SomeAsyncException -> String # showList :: [SomeAsyncException] -> ShowS # | |
| Exception SomeAsyncException | Since: base-4.7.0.0 |
Defined in GHC.IO.Exception Methods toException :: SomeAsyncException -> SomeException # fromException :: SomeException -> Maybe SomeAsyncException # | |
data IOException #
Exceptions that occur in the IO monad.
An IOException records a more specific error type, a descriptive
string and maybe the handle that was used when the error was
flagged.
Instances
class (Typeable e, Show e) => Exception e where #
Any type that you wish to throw or catch as an exception must be an
instance of the Exception class. The simplest case is a new exception
type directly below the root:
data MyException = ThisException | ThatException
deriving Show
instance Exception MyExceptionThe default method definitions in the Exception class do what we need
in this case. You can now throw and catch ThisException and
ThatException as exceptions:
*Main> throw ThisException `catch` \e -> putStrLn ("Caught " ++ show (e :: MyException))
Caught ThisException
In more complicated examples, you may wish to define a whole hierarchy of exceptions:
---------------------------------------------------------------------
-- Make the root exception type for all the exceptions in a compiler
data SomeCompilerException = forall e . Exception e => SomeCompilerException e
instance Show SomeCompilerException where
show (SomeCompilerException e) = show e
instance Exception SomeCompilerException
compilerExceptionToException :: Exception e => e -> SomeException
compilerExceptionToException = toException . SomeCompilerException
compilerExceptionFromException :: Exception e => SomeException -> Maybe e
compilerExceptionFromException x = do
SomeCompilerException a <- fromException x
cast a
---------------------------------------------------------------------
-- Make a subhierarchy for exceptions in the frontend of the compiler
data SomeFrontendException = forall e . Exception e => SomeFrontendException e
instance Show SomeFrontendException where
show (SomeFrontendException e) = show e
instance Exception SomeFrontendException where
toException = compilerExceptionToException
fromException = compilerExceptionFromException
frontendExceptionToException :: Exception e => e -> SomeException
frontendExceptionToException = toException . SomeFrontendException
frontendExceptionFromException :: Exception e => SomeException -> Maybe e
frontendExceptionFromException x = do
SomeFrontendException a <- fromException x
cast a
---------------------------------------------------------------------
-- Make an exception type for a particular frontend compiler exception
data MismatchedParentheses = MismatchedParentheses
deriving Show
instance Exception MismatchedParentheses where
toException = frontendExceptionToException
fromException = frontendExceptionFromExceptionWe can now catch a MismatchedParentheses exception as
MismatchedParentheses, SomeFrontendException or
SomeCompilerException, but not other types, e.g. IOException:
*Main> throw MismatchedParentheses `catch` \e -> putStrLn ("Caught " ++ show (e :: MismatchedParentheses))
Caught MismatchedParentheses
*Main> throw MismatchedParentheses `catch` \e -> putStrLn ("Caught " ++ show (e :: SomeFrontendException))
Caught MismatchedParentheses
*Main> throw MismatchedParentheses `catch` \e -> putStrLn ("Caught " ++ show (e :: SomeCompilerException))
Caught MismatchedParentheses
*Main> throw MismatchedParentheses `catch` \e -> putStrLn ("Caught " ++ show (e :: IOException))
*** Exception: MismatchedParentheses
Minimal complete definition
Nothing
Methods
toException :: e -> SomeException #
fromException :: SomeException -> Maybe e #
displayException :: e -> String #
Render this exception value in a human-friendly manner.
Default implementation: show
Since: base-4.8.0.0
Instances
data SomeException #
The SomeException type is the root of the exception type hierarchy.
When an exception of type e is thrown, behind the scenes it is
encapsulated in a SomeException.
Constructors
| Exception e => SomeException e |
Instances
| Show SomeException | Since: base-3.0 |
Defined in GHC.Exception.Type Methods showsPrec :: Int -> SomeException -> ShowS # show :: SomeException -> String # showList :: [SomeException] -> ShowS # | |
| AsError SomeException | |
| Exception SomeException | Since: base-3.0 |
Defined in GHC.Exception.Type Methods toException :: SomeException -> SomeException # fromException :: SomeException -> Maybe SomeException # displayException :: SomeException -> String # | |
class Monad m => MonadThrow (m :: Type -> Type) #
A class for monads in which exceptions may be thrown.
Instances should obey the following law:
throwM e >> x = throwM e
In other words, throwing an exception short-circuits the rest of the monadic computation.
Minimal complete definition
Instances
handleIOError :: MonadCatch m => (IOError -> m a) -> m a -> m a #
Flipped catchIOError
catchIOError :: MonadCatch m => m a -> (IOError -> m a) -> m a #
Catch all IOError (eqv. IOException) exceptions. Still somewhat too
general, but better than using catchAll. See catchIf for an easy way
of catching specific IOErrors based on the predicates in System.IO.Error.
uninterruptibleMask_ :: MonadMask m => m a -> m a #
Like uninterruptibleMask, but does not pass a restore action to the
argument.
class MonadThrow m => MonadCatch (m :: Type -> Type) #
A class for monads which allow exceptions to be caught, in particular
exceptions which were thrown by throwM.
Instances should obey the following law:
catch (throwM e) f = f e
Note that the ability to catch an exception does not guarantee that we can
deal with all possible exit points from a computation. Some monads, such as
continuation-based stacks, allow for more than just a success/failure
strategy, and therefore catch cannot be used by those monads to properly
implement a function such as finally. For more information, see
MonadMask.
Minimal complete definition
Instances
class MonadCatch m => MonadMask (m :: Type -> Type) where #
A class for monads which provide for the ability to account for all possible exit points from a computation, and to mask asynchronous exceptions. Continuation-based monads are invalid instances of this class.
Instances should ensure that, in the following code:
fg = f `finally` g
The action g is called regardless of what occurs within f, including
async exceptions. Some monads allow f to abort the computation via other
effects than throwing an exception. For simplicity, we will consider aborting
and throwing an exception to be two forms of "throwing an error".
If f and g both throw an error, the error thrown by fg depends on which
errors we're talking about. In a monad transformer stack, the deeper layers
override the effects of the inner layers; for example, ExceptT e1 (Except
e2) a represents a value of type Either e2 (Either e1 a), so throwing both
an e1 and an e2 will result in Left e2. If f and g both throw an
error from the same layer, instances should ensure that the error from g
wins.
Effects other than throwing an error are also overriden by the deeper layers.
For example, StateT s Maybe a represents a value of type s -> Maybe (a,
s), so if an error thrown from f causes this function to return Nothing,
any changes to the state which f also performed will be erased. As a
result, g will see the state as it was before f. Once g completes,
f's error will be rethrown, so g' state changes will be erased as well.
This is the normal interaction between effects in a monad transformer stack.
By contrast, lifted-base's
version of finally always discards all of g's non-IO effects, and g
never sees any of f's non-IO effects, regardless of the layer ordering and
regardless of whether f throws an error. This is not the result of
interacting effects, but a consequence of MonadBaseControl's approach.
Methods
mask :: ((forall a. m a -> m a) -> m b) -> m b #
Runs an action with asynchronous exceptions disabled. The action is
provided a method for restoring the async. environment to what it was
at the mask call. See Control.Exception's mask.
uninterruptibleMask :: ((forall a. m a -> m a) -> m b) -> m b #
Like mask, but the masked computation is not interruptible (see
Control.Exception's uninterruptibleMask. WARNING:
Only use if you need to mask exceptions around an interruptible operation
AND you can guarantee the interruptible operation will only block for a
short period of time. Otherwise you render the program/thread unresponsive
and/or unkillable.
Arguments
| :: m a | acquire some resource |
| -> (a -> ExitCase b -> m c) | release the resource, observing the outcome of the inner action |
| -> (a -> m b) | inner action to perform with the resource |
| -> m (b, c) |
A generalized version of bracket which uses ExitCase to distinguish
the different exit cases, and returns the values of both the use and
release actions. In practice, this extra information is rarely needed,
so it is often more convenient to use one of the simpler functions which
are defined in terms of this one, such as bracket, finally, onError,
and bracketOnError.
This function exists because in order to thread their effects through the
execution of bracket, monad transformers need values to be threaded from
use to release and from release to the output value.
NOTE This method was added in version 0.9.0 of this
library. Previously, implementation of functions like bracket
and finally in this module were based on the mask and
uninterruptibleMask functions only, disallowing some classes of
tranformers from having MonadMask instances (notably
multi-exit-point transformers like ExceptT). If you are a
library author, you'll now need to provide an implementation for
this method. The StateT implementation demonstrates most of the
subtleties:
generalBracket acquire release use = StateT $ s0 -> do
((b, _s2), (c, s3)) <- generalBracket
(runStateT acquire s0)
((resource, s1) exitCase -> case exitCase of
ExitCaseSuccess (b, s2) -> runStateT (release resource (ExitCaseSuccess b)) s2
-- In the two other cases, the base monad overrides use's state
-- changes and the state reverts to s1.
ExitCaseException e -> runStateT (release resource (ExitCaseException e)) s1
ExitCaseAbort -> runStateT (release resource ExitCaseAbort) s1
)
((resource, s1) -> runStateT (use resource) s1)
return ((b, c), s3)
The StateT s m implementation of generalBracket delegates to the m
implementation of generalBracket. The acquire, use, and release
arguments given to StateT's implementation produce actions of type
StateT s m a, StateT s m b, and StateT s m c. In order to run those
actions in the base monad, we need to call runStateT, from which we
obtain actions of type m (a, s), m (b, s), and m (c, s). Since each
action produces the next state, it is important to feed the state produced
by the previous action to the next action.
In the ExitCaseSuccess case, the state starts at s0, flows through
acquire to become s1, flows through use to become s2, and finally
flows through release to become s3. In the other two cases, release
does not receive the value s2, so its action cannot see the state changes
performed by use. This is fine, because in those two cases, an error was
thrown in the base monad, so as per the usual interaction between effects
in a monad transformer stack, those state changes get reverted. So we start
from s1 instead.
Finally, the m implementation of generalBracket returns the pairs
(b, s) and (c, s). For monad transformers other than StateT, this
will be some other type representing the effects and values performed and
returned by the use and release actions. The effect part of the use
result, in this case _s2, usually needs to be discarded, since those
effects have already been incorporated in the release action.
The only effect which is intentionally not incorporated in the release
action is the effect of throwing an error. In that case, the error must be
re-thrown. One subtlety which is easy to miss is that in the case in which
use and release both throw an error, the error from release should
take priority. Here is an implementation for ExceptT which demonstrates
how to do this.
generalBracket acquire release use = ExceptT $ do
(eb, ec) <- generalBracket
(runExceptT acquire)
(eresource exitCase -> case eresource of
Left e -> return (Left e) -- nothing to release, acquire didn't succeed
Right resource -> case exitCase of
ExitCaseSuccess (Right b) -> runExceptT (release resource (ExitCaseSuccess b))
ExitCaseException e -> runExceptT (release resource (ExitCaseException e))
_ -> runExceptT (release resource ExitCaseAbort))
(either (return . Left) (runExceptT . use))
return $ do
-- The order in which we perform those two Either effects determines
-- which error will win if they are both Lefts. We want the error from
-- release to win.
c <- ec
b <- eb
return (b, c)
Since: exceptions-0.9.0
Instances
| MonadMask IO | |
| e ~ SomeException => MonadMask (Either e) | Since: exceptions-0.8.3 |
Defined in Control.Monad.Catch | |
| MonadMask m => MonadMask (ResourceT m) | |
Defined in Control.Monad.Trans.Resource.Internal 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 # generalBracket :: ResourceT m a -> (a -> ExitCase b -> ResourceT m c) -> (a -> ResourceT m b) -> ResourceT m (b, c) # | |
| MonadMask m => MonadMask (MaybeT m) | Since: exceptions-0.10.0 |
Defined in Control.Monad.Catch | |
| MonadMask m => MonadMask (NoLoggingT m) | |
Defined in Control.Monad.Logger Methods mask :: ((forall a. NoLoggingT m a -> NoLoggingT m a) -> NoLoggingT m b) -> NoLoggingT m b # uninterruptibleMask :: ((forall a. NoLoggingT m a -> NoLoggingT m a) -> NoLoggingT m b) -> NoLoggingT m b # generalBracket :: NoLoggingT m a -> (a -> ExitCase b -> NoLoggingT m c) -> (a -> NoLoggingT m b) -> NoLoggingT m (b, c) # | |
| MonadMask m => MonadMask (WriterLoggingT m) | |
Defined in Control.Monad.Logger Methods mask :: ((forall a. WriterLoggingT m a -> WriterLoggingT m a) -> WriterLoggingT m b) -> WriterLoggingT m b # uninterruptibleMask :: ((forall a. WriterLoggingT m a -> WriterLoggingT m a) -> WriterLoggingT m b) -> WriterLoggingT m b # generalBracket :: WriterLoggingT m a -> (a -> ExitCase b -> WriterLoggingT m c) -> (a -> WriterLoggingT m b) -> WriterLoggingT m (b, c) # | |
| MonadMask m => MonadMask (LoggingT m) | |
Defined in Control.Monad.Logger Methods mask :: ((forall a. LoggingT m a -> LoggingT m a) -> LoggingT m b) -> LoggingT m b # uninterruptibleMask :: ((forall a. LoggingT m a -> LoggingT m a) -> LoggingT m b) -> LoggingT m b # generalBracket :: LoggingT m a -> (a -> ExitCase b -> LoggingT m c) -> (a -> LoggingT m b) -> LoggingT m (b, c) # | |
| MonadMask m => MonadMask (AWST' r m) | |
Defined in Control.Monad.Trans.AWS | |
| MonadMask m => MonadMask (IdentityT m) | |
Defined in Control.Monad.Catch Methods mask :: ((forall a. IdentityT m a -> IdentityT m a) -> IdentityT m b) -> IdentityT m b # uninterruptibleMask :: ((forall a. IdentityT m a -> IdentityT m a) -> IdentityT m b) -> IdentityT m b # generalBracket :: IdentityT m a -> (a -> ExitCase b -> IdentityT m c) -> (a -> IdentityT m b) -> IdentityT m (b, c) # | |
| (MonadMask m, Monoid w) => MonadMask (WriterT w m) | |
Defined in Control.Monad.Catch Methods mask :: ((forall a. WriterT w m a -> WriterT w m a) -> WriterT w m b) -> WriterT w m b # uninterruptibleMask :: ((forall a. WriterT w m a -> WriterT w m a) -> WriterT w m b) -> WriterT w m b # generalBracket :: WriterT w m a -> (a -> ExitCase b -> WriterT w m c) -> (a -> WriterT w m b) -> WriterT w m (b, c) # | |
| (MonadMask m, Monoid w) => MonadMask (WriterT w m) | |
Defined in Control.Monad.Catch Methods mask :: ((forall a. WriterT w m a -> WriterT w m a) -> WriterT w m b) -> WriterT w m b # uninterruptibleMask :: ((forall a. WriterT w m a -> WriterT w m a) -> WriterT w m b) -> WriterT w m b # generalBracket :: WriterT w m a -> (a -> ExitCase b -> WriterT w m c) -> (a -> WriterT w m b) -> WriterT w m (b, c) # | |
| MonadMask m => MonadMask (StateT s m) | |
Defined in Control.Monad.Catch Methods mask :: ((forall a. StateT s m a -> StateT s m a) -> StateT s m b) -> StateT s m b # uninterruptibleMask :: ((forall a. StateT s m a -> StateT s m a) -> StateT s m b) -> StateT s m b # generalBracket :: StateT s m a -> (a -> ExitCase b -> StateT s m c) -> (a -> StateT s m b) -> StateT s m (b, c) # | |
| MonadMask m => MonadMask (StateT s m) | |
Defined in Control.Monad.Catch Methods mask :: ((forall a. StateT s m a -> StateT s m a) -> StateT s m b) -> StateT s m b # uninterruptibleMask :: ((forall a. StateT s m a -> StateT s m a) -> StateT s m b) -> StateT s m b # generalBracket :: StateT s m a -> (a -> ExitCase b -> StateT s m c) -> (a -> StateT s m b) -> StateT s m (b, c) # | |
| MonadMask m => MonadMask (ReaderT r m) | |
Defined in Control.Monad.Catch Methods mask :: ((forall a. ReaderT r m a -> ReaderT r m a) -> ReaderT r m b) -> ReaderT r m b # uninterruptibleMask :: ((forall a. ReaderT r m a -> ReaderT r m a) -> ReaderT r m b) -> ReaderT r m b # generalBracket :: ReaderT r m a -> (a -> ExitCase b -> ReaderT r m c) -> (a -> ReaderT r m b) -> ReaderT r m (b, c) # | |
| MonadMask m => MonadMask (ExceptT e m) | Since: exceptions-0.9.0 |
Defined in Control.Monad.Catch Methods mask :: ((forall a. ExceptT e m a -> ExceptT e m a) -> ExceptT e m b) -> ExceptT e m b # uninterruptibleMask :: ((forall a. ExceptT e m a -> ExceptT e m a) -> ExceptT e m b) -> ExceptT e m b # generalBracket :: ExceptT e m a -> (a -> ExitCase b -> ExceptT e m c) -> (a -> ExceptT e m b) -> ExceptT e m (b, c) # | |
| (Error e, MonadMask m) => MonadMask (ErrorT e m) | |
Defined in Control.Monad.Catch Methods mask :: ((forall a. ErrorT e m a -> ErrorT e m a) -> ErrorT e m b) -> ErrorT e m b # uninterruptibleMask :: ((forall a. ErrorT e m a -> ErrorT e m a) -> ErrorT e m b) -> ErrorT e m b # generalBracket :: ErrorT e m a -> (a -> ExitCase b -> ErrorT e m c) -> (a -> ErrorT e m b) -> ErrorT e m (b, c) # | |
| (MonadMask m, Monoid w) => MonadMask (RWST r w s m) | |
Defined in Control.Monad.Catch Methods mask :: ((forall a. RWST r w s m a -> RWST r w s m a) -> RWST r w s m b) -> RWST r w s m b # uninterruptibleMask :: ((forall a. RWST r w s m a -> RWST r w s m a) -> RWST r w s m b) -> RWST r w s m b # generalBracket :: RWST r w s m a -> (a -> ExitCase b -> RWST r w s m c) -> (a -> RWST r w s m b) -> RWST r w s m (b, c) # | |
| (MonadMask m, Monoid w) => MonadMask (RWST r w s m) | |
Defined in Control.Monad.Catch Methods mask :: ((forall a. RWST r w s m a -> RWST r w s m a) -> RWST r w s m b) -> RWST r w s m b # uninterruptibleMask :: ((forall a. RWST r w s m a -> RWST r w s m a) -> RWST r w s m b) -> RWST r w s m b # generalBracket :: RWST r w s m a -> (a -> ExitCase b -> RWST r w s m c) -> (a -> RWST r w s m b) -> RWST r w s m (b, c) # | |
catchesAsync :: (MonadCatch m, MonadThrow m) => m a -> [Handler m a] -> m a #
catches without async exception safety
Generally it's better to avoid using this function since we do not want to recover from async exceptions, see https://github.com/fpco/safe-exceptions#quickstart
Since: safe-exceptions-0.1.2.0
catchesDeep :: (MonadCatch m, MonadThrow m, MonadIO m, NFData a) => m a -> [Handler m a] -> m a #
Same as catches, but fully force evaluation of the result value
to find all impure exceptions.
Since: safe-exceptions-0.1.2.0
catches :: (MonadCatch m, MonadThrow m) => m a -> [Handler m a] -> m a #
Same as upstream catches, but will not catch asynchronous
exceptions
Since: safe-exceptions-0.1.2.0
isAsyncException :: Exception e => e -> Bool #
Check if the given exception is asynchronous
Since: safe-exceptions-0.1.0.0
isSyncException :: Exception e => e -> Bool #
Check if the given exception is synchronous
Since: safe-exceptions-0.1.0.0
toAsyncException :: Exception e => e -> SomeException #
Convert an exception into an asynchronous exception
For asynchronous exceptions, this is the same as toException.
For synchronous exceptions, this will wrap up the exception with
AsyncExceptionWrapper
Since: safe-exceptions-0.1.0.0
toSyncException :: Exception e => e -> SomeException #
Convert an exception into a synchronous exception
For synchronous exceptions, this is the same as toException.
For asynchronous exceptions, this will wrap up the exception with
SyncExceptionWrapper
Since: safe-exceptions-0.1.0.0
bracketWithError :: MonadMask m => m a -> (Maybe SomeException -> a -> m b) -> (a -> m c) -> m c #
Async safe version of bracket with access to the exception in the
cleanup action.
Since: safe-exceptions-0.1.7.0
bracketOnError_ :: MonadMask m => m a -> m b -> m c -> m c #
A variant of bracketOnError where the return value from the first
computation is not required.
Since: safe-exceptions-0.1.0.0
bracketOnError :: MonadMask m => m a -> (a -> m b) -> (a -> m c) -> m c #
Async safe version of bracketOnError
Since: safe-exceptions-0.1.0.0
finally :: MonadMask m => m a -> m b -> m a #
Async safe version of finally
Since: safe-exceptions-0.1.0.0
bracket_ :: MonadMask m => m a -> m b -> m c -> m c #
Async safe version of bracket_
Since: safe-exceptions-0.1.0.0
bracket :: MonadMask m => m a -> (a -> m b) -> (a -> m c) -> m c #
Async safe version of bracket
Since: safe-exceptions-0.1.0.0
withException :: (MonadMask m, Exception e) => m a -> (e -> m b) -> m a #
Like onException, but provides the handler the thrown
exception.
Since: safe-exceptions-0.1.0.0
onException :: MonadMask m => m a -> m b -> m a #
Async safe version of onException
Since: safe-exceptions-0.1.0.0
tryJust :: (MonadCatch m, Exception e) => (e -> Maybe b) -> m a -> m (Either b a) #
A variant of try that takes an exception predicate to select
which exceptions are caught.
Since: safe-exceptions-0.1.4.0
tryAsync :: (MonadCatch m, Exception e) => m a -> m (Either e a) #
try without async exception safety
Generally it's better to avoid using this function since we do not want to recover from async exceptions, see https://github.com/fpco/safe-exceptions#quickstart
Since: safe-exceptions-0.1.0.0
tryAnyDeep :: (MonadCatch m, MonadIO m, NFData a) => m a -> m (Either SomeException a) #
tryDeep specialized to catch all synchronous exceptions
Since: safe-exceptions-0.1.1.0
tryDeep :: (MonadCatch m, MonadIO m, Exception e, NFData a) => m a -> m (Either e a) #
Same as try, but fully force evaluation of the result value
to find all impure exceptions.
Since: safe-exceptions-0.1.1.0
tryAny :: MonadCatch m => m a -> m (Either SomeException a) #
try specialized to catch all synchronous exceptions
Since: safe-exceptions-0.1.0.0
tryIO :: MonadCatch m => m a -> m (Either IOException a) #
try specialized to only catching IOExceptions
Since: safe-exceptions-0.1.3.0
try :: (MonadCatch m, Exception e) => m a -> m (Either e a) #
Same as upstream try, but will not catch asynchronous
exceptions
Since: safe-exceptions-0.1.0.0
handleJust :: (MonadCatch m, Exception e) => (e -> Maybe b) -> (b -> m a) -> m a -> m a #
Flipped catchJust.
Since: safe-exceptions-0.1.4.0
handleAsync :: (MonadCatch m, Exception e) => (e -> m a) -> m a -> m a #
Flipped version of catchAsync
Generally it's better to avoid using this function since we do not want to recover from async exceptions, see https://github.com/fpco/safe-exceptions#quickstart
Since: safe-exceptions-0.1.0.0
handleAnyDeep :: (MonadCatch m, MonadIO m, NFData a) => (SomeException -> m a) -> m a -> m a #
Flipped version of catchAnyDeep
Since: safe-exceptions-0.1.1.0
handleDeep :: (MonadCatch m, Exception e, MonadIO m, NFData a) => (e -> m a) -> m a -> m a #
Flipped version of catchDeep
Since: safe-exceptions-0.1.1.0
handleAny :: MonadCatch m => (SomeException -> m a) -> m a -> m a #
Flipped version of catchAny
Since: safe-exceptions-0.1.0.0
handleIO :: MonadCatch m => (IOException -> m a) -> m a -> m a #
handle specialized to only catching IOExceptions
Since: safe-exceptions-0.1.3.0
handle :: (MonadCatch m, Exception e) => (e -> m a) -> m a -> m a #
Flipped version of catch
Since: safe-exceptions-0.1.0.0
catchJust :: (MonadCatch m, Exception e) => (e -> Maybe b) -> m a -> (b -> m a) -> m a #
catchAsync :: (MonadCatch m, Exception e) => m a -> (e -> m a) -> m a #
catch without async exception safety
Generally it's better to avoid using this function since we do not want to recover from async exceptions, see https://github.com/fpco/safe-exceptions#quickstart
Since: safe-exceptions-0.1.0.0
catchAnyDeep :: (MonadCatch m, MonadIO m, NFData a) => m a -> (SomeException -> m a) -> m a #
catchDeep specialized to catch all synchronous exception
Since: safe-exceptions-0.1.1.0
catchDeep :: (MonadCatch m, MonadIO m, Exception e, NFData a) => m a -> (e -> m a) -> m a #
Same as catch, but fully force evaluation of the result value
to find all impure exceptions.
Since: safe-exceptions-0.1.1.0
catchAny :: MonadCatch m => m a -> (SomeException -> m a) -> m a #
catch specialized to catch all synchronous exception
Since: safe-exceptions-0.1.0.0
catch :: (MonadCatch m, Exception e) => m a -> (e -> m a) -> m a #
Same as upstream catch, but will not catch asynchronous
exceptions
Since: safe-exceptions-0.1.0.0
impureThrow :: Exception e => e -> a #
Generate a pure value which, when forced, will synchronously throw the given exception
Generally it's better to avoid using this function and instead use throw,
see https://github.com/fpco/safe-exceptions#quickstart
Since: safe-exceptions-0.1.0.0
throwTo :: (Exception e, MonadIO m) => ThreadId -> e -> m () #
Throw an asynchronous exception to another thread.
Synchronously typed exceptions will be wrapped into an
AsyncExceptionWrapper, see
https://github.com/fpco/safe-exceptions#determining-sync-vs-async
It's usually a better idea to use the async package, see https://github.com/fpco/safe-exceptions#quickstart
Since: safe-exceptions-0.1.0.0
throwString :: (MonadThrow m, HasCallStack) => String -> m a #
A convenience function for throwing a user error. This is useful for cases where it would be too high a burden to define your own exception type.
This throws an exception of type StringException. When GHC
supports it (base 4.9 and GHC 8.0 and onward), it includes a call
stack.
Since: safe-exceptions-0.1.5.0
throwIO :: (MonadThrow m, Exception e) => e -> m a #
Synonym for throw
Since: safe-exceptions-0.1.0.0
throw :: (MonadThrow m, Exception e) => e -> m a #
Synchronously throw the given exception
Since: safe-exceptions-0.1.0.0
data StringException #
Exception type thrown by throwString.
Note that the second field of the data constructor depends on GHC/base version. For base 4.9 and GHC 8.0 and later, the second field is a call stack. Previous versions of GHC and base do not support call stacks, and the field is simply unit (provided to make pattern matching across GHC versions easier).
Since: safe-exceptions-0.1.5.0
Constructors
| StringException String CallStack |
Instances
| Show StringException | |
Defined in Control.Exception.Safe Methods showsPrec :: Int -> StringException -> ShowS # show :: StringException -> String # showList :: [StringException] -> ShowS # | |
| Exception StringException | |
Defined in Control.Exception.Safe Methods toException :: StringException -> SomeException # | |
data SyncExceptionWrapper #
Wrap up an asynchronous exception to be treated as a synchronous exception
This is intended to be created via toSyncException
Since: safe-exceptions-0.1.0.0
Constructors
| Exception e => SyncExceptionWrapper e |
Instances
| Show SyncExceptionWrapper | |
Defined in Control.Exception.Safe Methods showsPrec :: Int -> SyncExceptionWrapper -> ShowS # show :: SyncExceptionWrapper -> String # showList :: [SyncExceptionWrapper] -> ShowS # | |
| Exception SyncExceptionWrapper | |
Defined in Control.Exception.Safe Methods toException :: SyncExceptionWrapper -> SomeException # fromException :: SomeException -> Maybe SyncExceptionWrapper # | |
data AsyncExceptionWrapper #
Wrap up a synchronous exception to be treated as an asynchronous exception
This is intended to be created via toAsyncException
Since: safe-exceptions-0.1.0.0
Constructors
| Exception e => AsyncExceptionWrapper e |
Instances
| Show AsyncExceptionWrapper | |
Defined in Control.Exception.Safe Methods showsPrec :: Int -> AsyncExceptionWrapper -> ShowS # show :: AsyncExceptionWrapper -> String # showList :: [AsyncExceptionWrapper] -> ShowS # | |
| Exception AsyncExceptionWrapper | |
Defined in Control.Exception.Safe | |
data AsyncException #
Asynchronous exceptions.
Constructors
| StackOverflow | The current thread's stack exceeded its limit. Since an exception has been raised, the thread's stack will certainly be below its limit again, but the programmer should take remedial action immediately. |
| HeapOverflow | The program's heap is reaching its limit, and the program should take action to reduce the amount of live data it has. Notes:
|
| ThreadKilled | This exception is raised by another thread
calling |
| UserInterrupt | This exception is raised by default in the main thread of the program when the user requests to terminate the program via the usual mechanism(s) (e.g. Control-C in the console). |
Instances
Exception functions
catchIf :: (MonadCatch m, Exception e) => (e -> Bool) -> m a -> (e -> m a) -> m a Source #
Catch exception based on a predicate
unsafeEvaluate :: a -> IO a Source #
Function alias for Control.Exception.evaluate
unsafeThrow :: Exception e => e -> a Source #
Function alias for Control.Exception.throw