unliftio-0.2.25.0: The MonadUnliftIO typeclass for unlifting monads to IO (batteries included)
Safe HaskellNone
LanguageHaskell2010

UnliftIO.Exception

Description

Unlifted Control.Exception, with extra async exception safety and more helper functions.

This module works best when your cleanup functions adhere to certain expectations around exception safety and interruptible actions. For more details, see this exception safety tutorial.

Synopsis

Throwing

throwIO :: (MonadIO m, Exception e) => e -> m a Source #

Synchronously throw the given exception.

Note that, if you provide an exception value which is of an asynchronous type, it will be wrapped up in SyncExceptionWrapper. See toSyncException.

Since: 0.1.0.0

throwString :: (MonadIO m, HasCallStack) => String -> m a Source #

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: 0.1.0.0

data StringException Source #

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: 0.1.0.0

Constructors

StringException String CallStack 

Instances

Instances details
Exception StringException Source #

Since: 0.1.0.0

Instance details

Defined in UnliftIO.Exception

Show StringException Source #

Since: 0.1.0.0

Instance details

Defined in UnliftIO.Exception

Methods

showsPrec :: Int -> StringException -> ShowS

show :: StringException -> String

showList :: [StringException] -> ShowS

Eq StringException Source #

Since: 0.2.19

Instance details

Defined in UnliftIO.Exception

stringException :: HasCallStack => String -> StringException Source #

Smart constructor for a StringException that deals with the call stack.

Since: 0.1.0.0

throwTo :: (Exception e, MonadIO m) => ThreadId -> e -> m () Source #

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 UnliftIO.Async module, see https://github.com/fpco/safe-exceptions#quickstart.

Since: 0.1.0.0

impureThrow :: Exception e => e -> a Source #

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 throwIO, see https://github.com/fpco/safe-exceptions#quickstart.

Since: 0.1.0.0

fromEither :: (Exception e, MonadIO m) => Either e a -> m a Source #

Unwrap an Either value, throwing its Left value as a runtime exception via throwIO if present.

Since: 0.1.0.0

fromEitherIO :: (Exception e, MonadIO m) => IO (Either e a) -> m a Source #

Same as fromEither, but works on an IO-wrapped Either.

Since: 0.1.0.0

fromEitherM :: (Exception e, MonadIO m) => m (Either e a) -> m a Source #

Same as fromEither, but works on an m-wrapped Either.

Since: 0.1.0.0

mapExceptionM :: (Exception e1, Exception e2, MonadUnliftIO m) => (e1 -> e2) -> m a -> m a Source #

Same as mapException, except works in a monadic context.

Since: 0.2.15

Catching (with recovery)

catch Source #

Arguments

:: (MonadUnliftIO m, Exception e) 
=> m a

action

-> (e -> m a)

handler

-> m a 

Catch a synchronous (but not asynchronous) exception and recover from it.

This is parameterized on the exception type. To catch all synchronous exceptions, use catchAny.

Since: 0.1.0.0

catchIO :: MonadUnliftIO m => m a -> (IOException -> m a) -> m a Source #

catch specialized to only catching IOExceptions.

Since: 0.1.0.0

catchAny :: MonadUnliftIO m => m a -> (SomeException -> m a) -> m a Source #

catch specialized to catch all synchronous exceptions.

Since: 0.1.0.0

catchDeep :: (MonadUnliftIO m, Exception e, NFData a) => m a -> (e -> m a) -> m a Source #

Same as catch, but fully force evaluation of the result value to find all impure exceptions.

Since: 0.1.0.0

catchAnyDeep :: (NFData a, MonadUnliftIO m) => m a -> (SomeException -> m a) -> m a Source #

catchDeep specialized to catch all synchronous exception.

Since: 0.1.0.0

catchJust :: (MonadUnliftIO m, Exception e) => (e -> Maybe b) -> m a -> (b -> m a) -> m a Source #

catchJust is like catch but it takes an extra argument which is an exception predicate, a function which selects which type of exceptions we're interested in.

Since: 0.1.0.0

handle :: (MonadUnliftIO m, Exception e) => (e -> m a) -> m a -> m a Source #

Flipped version of catch.

Since: 0.1.0.0

handleIO :: MonadUnliftIO m => (IOException -> m a) -> m a -> m a Source #

handle specialized to only catching IOExceptions.

Since: 0.1.0.0

handleAny :: MonadUnliftIO m => (SomeException -> m a) -> m a -> m a Source #

Flipped version of catchAny.

Since: 0.1.0.0

handleDeep :: (MonadUnliftIO m, Exception e, NFData a) => (e -> m a) -> m a -> m a Source #

Flipped version of catchDeep.

Since: 0.1.0.0

handleAnyDeep :: (MonadUnliftIO m, NFData a) => (SomeException -> m a) -> m a -> m a Source #

Flipped version of catchAnyDeep.

Since: 0.1.0.0

handleJust :: (MonadUnliftIO m, Exception e) => (e -> Maybe b) -> (b -> m a) -> m a -> m a Source #

Flipped catchJust.

Since: 0.1.0.0

try :: (MonadUnliftIO m, Exception e) => m a -> m (Either e a) Source #

Run the given action and catch any synchronous exceptions as a Left value.

This is parameterized on the exception type. To catch all synchronous exceptions, use tryAny.

Since: 0.1.0.0

tryIO :: MonadUnliftIO m => m a -> m (Either IOException a) Source #

try specialized to only catching IOExceptions.

Since: 0.1.0.0

tryAny :: MonadUnliftIO m => m a -> m (Either SomeException a) Source #

try specialized to catch all synchronous exceptions.

Since: 0.1.0.0

tryDeep :: (MonadUnliftIO m, Exception e, NFData a) => m a -> m (Either e a) Source #

Same as try, but fully force evaluation of the result value to find all impure exceptions.

Since: 0.1.0.0

tryAnyDeep :: (MonadUnliftIO m, NFData a) => m a -> m (Either SomeException a) Source #

tryDeep specialized to catch all synchronous exceptions.

Since: 0.1.0.0

tryJust :: (MonadUnliftIO m, Exception e) => (e -> Maybe b) -> m a -> m (Either b a) Source #

A variant of try that takes an exception predicate to select which exceptions are caught.

Since: 0.1.0.0

pureTry :: a -> Either SomeException a Source #

Evaluate the value to WHNF and catch any synchronous exceptions.

The expression may still have bottom values within it; you may instead want to use pureTryDeep.

Since: 0.2.2.0

pureTryDeep :: NFData a => a -> Either SomeException a Source #

Evaluate the value to NF and catch any synchronous exceptions.

Since: 0.2.2.0

data Handler (m :: Type -> Type) a #

Constructors

Exception e => Handler (e -> m a) 

Instances

Instances details
Monad m => Functor (Handler m) 
Instance details

Defined in Control.Monad.Catch

Methods

fmap :: (a -> b) -> Handler m a -> Handler m b

(<$) :: a -> Handler m b -> Handler m a

catches :: MonadUnliftIO m => m a -> [Handler m a] -> m a Source #

Similar to catch, but provides multiple different handler functions.

For more information on motivation, see base's catches. Note that, unlike that function, this function will not catch asynchronous exceptions.

Since: 0.1.0.0

catchesDeep :: (MonadUnliftIO m, NFData a) => m a -> [Handler m a] -> m a Source #

Same as catches, but fully force evaluation of the result value to find all impure exceptions.

Since: 0.1.0.0

Catching async exceptions (with recovery)

catchSyncOrAsync :: (MonadUnliftIO m, Exception e) => m a -> (e -> m a) -> m a Source #

A variant of catch that catches both synchronous and asynchronous exceptions.

WARNING: This function (and other *SyncOrAsync functions) is for advanced users. Most of the time, you probably want to use the non-SyncOrAsync versions.

Before attempting to use this function, be familiar with the "Rules for async safe handling" section in this blog post.

Since: 0.2.17

handleSyncOrAsync :: (MonadUnliftIO m, Exception e) => (e -> m a) -> m a -> m a Source #

A variant of handle that catches both synchronous and asynchronous exceptions.

See catchSyncOrAsync.

Since: 0.2.17

trySyncOrAsync :: (MonadUnliftIO m, Exception e) => m a -> m (Either e a) Source #

A variant of try that catches both synchronous and asynchronous exceptions.

See catchSyncOrAsync.

Since: 0.2.17

Cleanup (no recovery)

onException :: MonadUnliftIO m => m a -> m b -> m a Source #

Like finally, but only call after if an exception occurs.

Since: 0.1.0.0

bracket :: MonadUnliftIO m => m a -> (a -> m b) -> (a -> m c) -> m c Source #

Allocate and clean up a resource safely.

For more information on motivation and usage of this function, see base's bracket. This function has two differences from the one in base. The first, and more obvious, is that it works on any MonadUnliftIO instance, not just IO.

The more subtle difference is that this function will use uninterruptible masking for its cleanup handler. This is a subtle distinction, but at a high level, means that resource cleanup has more guarantees to complete. This comes at the cost that an incorrectly written cleanup function cannot be interrupted.

For more information, please see https://github.com/fpco/safe-exceptions/issues/3.

Since: 0.1.0.0

bracket_ :: MonadUnliftIO m => m a -> m b -> m c -> m c Source #

Same as bracket, but does not pass the acquired resource to cleanup and use functions.

For more information, see base's bracket_.

Since: 0.1.0.0

finally Source #

Arguments

:: MonadUnliftIO m 
=> m a

thing

-> m b

after

-> m a 

Perform thing, guaranteeing that after will run after, even if an exception occurs.

Same interruptible vs uninterrupible points apply as with bracket. See base's finally for more information.

Since: 0.1.0.0

withException :: (MonadUnliftIO m, Exception e) => m a -> (e -> m b) -> m a Source #

Like onException, but provides the handler the thrown exception.

Since: 0.1.0.0

bracketOnError :: MonadUnliftIO m => m a -> (a -> m b) -> (a -> m c) -> m c Source #

Same as bracket, but only perform the cleanup if an exception is thrown.

Since: 0.1.0.0

bracketOnError_ :: MonadUnliftIO m => m a -> m b -> m c -> m c Source #

A variant of bracketOnError where the return value from the first computation is not required.

Since: 0.1.0.0

Coercion to sync and async

In version 0.2.23.0, these were changed with aliases to the values from Control.Exception.Safe in the safe-exceptions package.

toSyncException :: Exception e => e -> SomeException Source #

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: 0.1.0.0

toAsyncException :: Exception e => e -> SomeException Source #

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: 0.1.0.0

fromExceptionUnwrap :: Exception e => SomeException -> Maybe e Source #

Convert from a possibly wrapped exception.

The inverse of toAsyncException and toSyncException. When using those functions (or functions that use them, like throwTo or throwIO), fromException might not be sufficient because the exception might be wrapped within SyncExceptionWrapper or AsyncExceptionWrapper.

Since: 0.2.17

Check exception type

isSyncException :: Exception e => e -> Bool Source #

Check if the given exception is synchronous.

Since: 0.1.0.0

isAsyncException :: Exception e => e -> Bool Source #

Check if the given exception is asynchronous.

Since: 0.1.0.0

Masking

mask :: MonadUnliftIO m => ((forall a. m a -> m a) -> m b) -> m b Source #

Unlifted version of mask.

Since: 0.1.0.0

uninterruptibleMask :: MonadUnliftIO m => ((forall a. m a -> m a) -> m b) -> m b Source #

Unlifted version of uninterruptibleMask.

Since: 0.1.0.0

mask_ :: MonadUnliftIO m => m a -> m a Source #

Unlifted version of mask_.

Since: 0.1.0.0

uninterruptibleMask_ :: MonadUnliftIO m => m a -> m a Source #

Unlifted version of uninterruptibleMask_.

Since: 0.1.0.0

Evaluation

evaluate :: MonadIO m => a -> m a Source #

Lifted version of evaluate.

Since: 0.1.0.0

evaluateDeep :: (MonadIO m, NFData a) => a -> m a Source #

Deeply evaluate a value using evaluate and NFData.

Since: 0.1.0.0

Reexports

class (Typeable e, Show e) => Exception e where #

Minimal complete definition

Nothing

Methods

toException :: e -> SomeException #

fromException :: SomeException -> Maybe e #

displayException :: e -> String #

Instances

Instances details
Exception AsyncCancelled 
Instance details

Defined in Control.Concurrent.Async.Internal

Exception ExceptionInLinkedThread 
Instance details

Defined in Control.Concurrent.Async.Internal

Methods

toException :: ExceptionInLinkedThread -> SomeException #

fromException :: SomeException -> Maybe ExceptionInLinkedThread #

displayException :: ExceptionInLinkedThread -> String #

Exception NestedAtomically 
Instance details

Defined in Control.Exception.Base

Methods

toException :: NestedAtomically -> SomeException #

fromException :: SomeException -> Maybe NestedAtomically #

displayException :: NestedAtomically -> String #

Exception NoMatchingContinuationPrompt 
Instance details

Defined in Control.Exception.Base

Methods

toException :: NoMatchingContinuationPrompt -> SomeException #

fromException :: SomeException -> Maybe NoMatchingContinuationPrompt #

displayException :: NoMatchingContinuationPrompt -> String #

Exception NoMethodError 
Instance details

Defined in Control.Exception.Base

Methods

toException :: NoMethodError -> SomeException #

fromException :: SomeException -> Maybe NoMethodError #

displayException :: NoMethodError -> String #

Exception NonTermination 
Instance details

Defined in Control.Exception.Base

Methods

toException :: NonTermination -> SomeException #

fromException :: SomeException -> Maybe NonTermination #

displayException :: NonTermination -> String #

Exception PatternMatchFail 
Instance details

Defined in Control.Exception.Base

Methods

toException :: PatternMatchFail -> SomeException #

fromException :: SomeException -> Maybe PatternMatchFail #

displayException :: PatternMatchFail -> String #

Exception RecConError 
Instance details

Defined in Control.Exception.Base

Methods

toException :: RecConError -> SomeException #

fromException :: SomeException -> Maybe RecConError #

displayException :: RecConError -> String #

Exception RecSelError 
Instance details

Defined in Control.Exception.Base

Methods

toException :: RecSelError -> SomeException #

fromException :: SomeException -> Maybe RecSelError #

displayException :: RecSelError -> String #

Exception RecUpdError 
Instance details

Defined in Control.Exception.Base

Methods

toException :: RecUpdError -> SomeException #

fromException :: SomeException -> Maybe RecUpdError #

displayException :: RecUpdError -> String #

Exception TypeError 
Instance details

Defined in Control.Exception.Base

Methods

toException :: TypeError -> SomeException #

fromException :: SomeException -> Maybe TypeError #

displayException :: TypeError -> String #

Exception Dynamic 
Instance details

Defined in Data.Dynamic

Methods

toException :: Dynamic -> SomeException #

fromException :: SomeException -> Maybe Dynamic #

displayException :: Dynamic -> String #

Exception Void 
Instance details

Defined in GHC.Exception.Type

Methods

toException :: Void -> SomeException #

fromException :: SomeException -> Maybe Void #

displayException :: Void -> String #

Exception ErrorCall 
Instance details

Defined in GHC.Exception

Methods

toException :: ErrorCall -> SomeException #

fromException :: SomeException -> Maybe ErrorCall #

displayException :: ErrorCall -> String #

Exception ArithException 
Instance details

Defined in GHC.Exception.Type

Methods

toException :: ArithException -> SomeException #

fromException :: SomeException -> Maybe ArithException #

displayException :: ArithException -> String #

Exception SomeException 
Instance details

Defined in GHC.Exception.Type

Exception AllocationLimitExceeded 
Instance details

Defined in GHC.IO.Exception

Methods

toException :: AllocationLimitExceeded -> SomeException #

fromException :: SomeException -> Maybe AllocationLimitExceeded #

displayException :: AllocationLimitExceeded -> String #

Exception ArrayException 
Instance details

Defined in GHC.IO.Exception

Methods

toException :: ArrayException -> SomeException #

fromException :: SomeException -> Maybe ArrayException #

displayException :: ArrayException -> String #

Exception AssertionFailed 
Instance details

Defined in GHC.IO.Exception

Methods

toException :: AssertionFailed -> SomeException #

fromException :: SomeException -> Maybe AssertionFailed #

displayException :: AssertionFailed -> String #

Exception AsyncException 
Instance details

Defined in GHC.IO.Exception

Methods

toException :: AsyncException -> SomeException #

fromException :: SomeException -> Maybe AsyncException #

displayException :: AsyncException -> String #

Exception BlockedIndefinitelyOnMVar 
Instance details

Defined in GHC.IO.Exception

Methods

toException :: BlockedIndefinitelyOnMVar -> SomeException #

fromException :: SomeException -> Maybe BlockedIndefinitelyOnMVar #

displayException :: BlockedIndefinitelyOnMVar -> String #

Exception BlockedIndefinitelyOnSTM 
Instance details

Defined in GHC.IO.Exception

Methods

toException :: BlockedIndefinitelyOnSTM -> SomeException #

fromException :: SomeException -> Maybe BlockedIndefinitelyOnSTM #

displayException :: BlockedIndefinitelyOnSTM -> String #

Exception CompactionFailed 
Instance details

Defined in GHC.IO.Exception

Methods

toException :: CompactionFailed -> SomeException #

fromException :: SomeException -> Maybe CompactionFailed #

displayException :: CompactionFailed -> String #

Exception Deadlock 
Instance details

Defined in GHC.IO.Exception

Methods

toException :: Deadlock -> SomeException #

fromException :: SomeException -> Maybe Deadlock #

displayException :: Deadlock -> String #

Exception ExitCode 
Instance details

Defined in GHC.IO.Exception

Methods

toException :: ExitCode -> SomeException #

fromException :: SomeException -> Maybe ExitCode #

displayException :: ExitCode -> String #

Exception FixIOException 
Instance details

Defined in GHC.IO.Exception

Methods

toException :: FixIOException -> SomeException #

fromException :: SomeException -> Maybe FixIOException #

displayException :: FixIOException -> String #

Exception IOException 
Instance details

Defined in GHC.IO.Exception

Exception SomeAsyncException 
Instance details

Defined in GHC.IO.Exception

Exception IOPortException 
Instance details

Defined in GHC.IOPort

Methods

toException :: IOPortException -> SomeException #

fromException :: SomeException -> Maybe IOPortException #

displayException :: IOPortException -> String #

Exception Timeout 
Instance details

Defined in System.Timeout

Methods

toException :: Timeout -> SomeException #

fromException :: SomeException -> Maybe Timeout #

displayException :: Timeout -> String #

Exception SizeOverflowException 
Instance details

Defined in Data.ByteString.Internal.Type

Methods

toException :: SizeOverflowException -> SomeException #

fromException :: SomeException -> Maybe SizeOverflowException #

displayException :: SizeOverflowException -> String #

Exception AsyncExceptionWrapper 
Instance details

Defined in Control.Exception.Safe

Exception StringException 
Instance details

Defined in Control.Exception.Safe

Methods

toException :: StringException -> SomeException #

fromException :: SomeException -> Maybe StringException #

displayException :: StringException -> String #

Exception SyncExceptionWrapper 
Instance details

Defined in Control.Exception.Safe

Exception StringException Source #

Since: 0.1.0.0

Instance details

Defined in UnliftIO.Exception

Exception ConcException Source # 
Instance details

Defined in UnliftIO.Internals.Async

class Typeable (a :: k) #

Minimal complete definition

typeRep#

data SomeException #

Constructors

Exception e => SomeException e 

Instances

Instances details
Exception SomeException 
Instance details

Defined in GHC.Exception.Type

Show SomeException 
Instance details

Defined in GHC.Exception.Type

Methods

showsPrec :: Int -> SomeException -> ShowS

show :: SomeException -> String

showList :: [SomeException] -> ShowS

data SomeAsyncException #

Constructors

Exception e => SomeAsyncException e 

Instances

Instances details
Exception SomeAsyncException 
Instance details

Defined in GHC.IO.Exception

Show SomeAsyncException 
Instance details

Defined in GHC.IO.Exception

Methods

showsPrec :: Int -> SomeAsyncException -> ShowS

show :: SomeAsyncException -> String

showList :: [SomeAsyncException] -> ShowS

data IOException #

Instances

Instances details
Exception IOException 
Instance details

Defined in GHC.IO.Exception

Show IOException 
Instance details

Defined in GHC.IO.Exception

Methods

showsPrec :: Int -> IOException -> ShowS

show :: IOException -> String

showList :: [IOException] -> ShowS

Eq IOException 
Instance details

Defined in GHC.IO.Exception

Methods

(==) :: IOException -> IOException -> Bool

(/=) :: IOException -> IOException -> Bool

assert :: Bool -> a -> a #