lifted-base-0.2.3.12: lifted IO operations from the base library

Copyright | Bas van Dijk Anders Kaseorg
License | BSD-style
Maintainer | Bas van Dijk <v.dijk.bas@gmail.com>
Stability | experimental
Portability | non-portable (extended exceptions)
Safe Haskell | Safe
Language | Haskell98

Control.Exception.Lifted

Contents

- Throwing exceptions
- Catching exceptions
  - The `catch` functions
  - The `handle` functions
  - The `try` functions
  - The `evaluate` function
- Asynchronous Exceptions
  - Asynchronous exception control
- Brackets
- Utilities

Description

This is a wrapped version of Control.Exception with types generalized from `IO` to all monads in either `MonadBase` or `MonadBaseControl`.

Synopsis

- newtype AssertionFailed = AssertionFailed String
- class (Typeable e, Show e) => Exception e where
  - toException :: e -> SomeException
  - fromException :: SomeException -> Maybe e
  - displayException :: e -> String
- data SomeException = Exception e => SomeException e
- data IOException
- data BlockedIndefinitelyOnMVar = BlockedIndefinitelyOnMVar
- newtype TypeError = TypeError String
- data ArithException
  - = Overflow
  - | Underflow
  - | LossOfPrecision
  - | DivideByZero
  - | Denormal
  - | RatioZeroDenominator
- data ErrorCall where
  - ErrorCallWithLocation String String
  - pattern ErrorCall :: String -> ErrorCall
- data MaskingState
  - = Unmasked
  - | MaskedInterruptible
  - | MaskedUninterruptible
- data ArrayException
  - = IndexOutOfBounds String
  - | UndefinedElement String
- data AsyncException
  - = StackOverflow
  - | HeapOverflow
  - | ThreadKilled
  - | UserInterrupt
- data SomeAsyncException = Exception e => SomeAsyncException e
- newtype CompactionFailed = CompactionFailed String
- data AllocationLimitExceeded = AllocationLimitExceeded
- data Deadlock = Deadlock
- data BlockedIndefinitelyOnSTM = BlockedIndefinitelyOnSTM
- data NestedAtomically = NestedAtomically
- data NonTermination = NonTermination
- newtype NoMethodError = NoMethodError String
- newtype RecUpdError = RecUpdError String
- newtype RecConError = RecConError String
- newtype RecSelError = RecSelError String
- newtype PatternMatchFail = PatternMatchFail String
- throw :: forall (r :: RuntimeRep) (a :: TYPE r) e. Exception e => e -> a
- assert :: Bool -> a -> a
- interruptible :: IO a -> IO a
- asyncExceptionToException :: Exception e => e -> SomeException
- asyncExceptionFromException :: Exception e => SomeException -> Maybe e
- mapException :: (Exception e1, Exception e2) => (e1 -> e2) -> a -> a
- throwIO :: (MonadBase IO m, Exception e) => e -> m a
- ioError :: MonadBase IO m => IOError -> m a
- throwTo :: (MonadBase IO m, Exception e) => ThreadId -> e -> m ()
- catch :: (MonadBaseControl IO m, Exception e) => m a -> (e -> m a) -> m a
- catches :: MonadBaseControl IO m => m a -> [Handler m a] -> m a
- data Handler m a = forall e.Exception e => Handler (e -> m a)
- catchJust :: (MonadBaseControl IO m, Exception e) => (e -> Maybe b) -> m a -> (b -> m a) -> m a
- handle :: (MonadBaseControl IO m, Exception e) => (e -> m a) -> m a -> m a
- handleJust :: (MonadBaseControl IO m, Exception e) => (e -> Maybe b) -> (b -> m a) -> m a -> m a
- try :: (MonadBaseControl IO m, Exception e) => m a -> m (Either e a)
- tryJust :: (MonadBaseControl IO m, Exception e) => (e -> Maybe b) -> m a -> m (Either b a)
- evaluate :: MonadBase IO m => a -> m a
- mask :: MonadBaseControl IO m => ((forall a. m a -> m a) -> m b) -> m b
- mask_ :: MonadBaseControl IO m => m a -> m a
- uninterruptibleMask :: MonadBaseControl IO m => ((forall a. m a -> m a) -> m b) -> m b
- uninterruptibleMask_ :: MonadBaseControl IO m => m a -> m a
- getMaskingState :: MonadBase IO m => m MaskingState
- allowInterrupt :: MonadBase IO m => m ()
- bracket :: MonadBaseControl IO m => m a -> (a -> m b) -> (a -> m c) -> m c
- bracket_ :: MonadBaseControl IO m => m a -> m b -> m c -> m c
- bracketOnError :: MonadBaseControl IO m => m a -> (a -> m b) -> (a -> m c) -> m c
- finally :: MonadBaseControl IO m => m a -> m b -> m a
- onException :: MonadBaseControl IO m => m a -> m b -> m a

# Documentation

newtype AssertionFailed Source #

`assert` was applied to `False`.

Constructors

AssertionFailed String |

#### Instances

Instances details

Exception AssertionFailed | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: AssertionFailed -> SomeException Source # fromException :: SomeException -> Maybe AssertionFailed Source # displayException :: AssertionFailed -> String Source #
Show AssertionFailed | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods showsPrec :: Int -> AssertionFailed -> ShowS Source # show :: AssertionFailed -> String Source # showList :: [AssertionFailed] -> ShowS Source #

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

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 MyException

The 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 = frontendExceptionFromException

We 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 Source #

fromException :: SomeException -> Maybe e Source #

displayException :: e -> String Source #

Render this exception value in a human-friendly manner.

Default implementation: ``show``.

Since: base-4.8.0.0

#### Instances

Instances details

Exception NestedAtomically | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: NestedAtomically -> SomeException Source # fromException :: SomeException -> Maybe NestedAtomically Source # displayException :: NestedAtomically -> String Source #
Exception NoMethodError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: NoMethodError -> SomeException Source # fromException :: SomeException -> Maybe NoMethodError Source # displayException :: NoMethodError -> String Source #
Exception NonTermination | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: NonTermination -> SomeException Source # fromException :: SomeException -> Maybe NonTermination Source # displayException :: NonTermination -> String Source #
Exception PatternMatchFail | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: PatternMatchFail -> SomeException Source # fromException :: SomeException -> Maybe PatternMatchFail Source # displayException :: PatternMatchFail -> String Source #
Exception RecConError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: RecConError -> SomeException Source # fromException :: SomeException -> Maybe RecConError Source # displayException :: RecConError -> String Source #
Exception RecSelError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: RecSelError -> SomeException Source # fromException :: SomeException -> Maybe RecSelError Source # displayException :: RecSelError -> String Source #
Exception RecUpdError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: RecUpdError -> SomeException Source # fromException :: SomeException -> Maybe RecUpdError Source # displayException :: RecUpdError -> String Source #
Exception TypeError | Since: base-4.9.0.0
Instance details Defined in Control.Exception.Base Methods toException :: TypeError -> SomeException Source # fromException :: SomeException -> Maybe TypeError Source # displayException :: TypeError -> String Source #
Exception ErrorCall | Since: base-4.0.0.0
Instance details Defined in GHC.Exception Methods toException :: ErrorCall -> SomeException Source # fromException :: SomeException -> Maybe ErrorCall Source # displayException :: ErrorCall -> String Source #
Exception ArithException | Since: base-4.0.0.0
Instance details Defined in GHC.Exception.Type Methods toException :: ArithException -> SomeException Source # fromException :: SomeException -> Maybe ArithException Source # displayException :: ArithException -> String Source #
Exception SomeException | Since: base-3.0
Instance details Defined in GHC.Exception.Type Methods toException :: SomeException -> SomeException Source # fromException :: SomeException -> Maybe SomeException Source # displayException :: SomeException -> String Source #
Exception AllocationLimitExceeded | Since: base-4.8.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: AllocationLimitExceeded -> SomeException Source # fromException :: SomeException -> Maybe AllocationLimitExceeded Source # displayException :: AllocationLimitExceeded -> String Source #
Exception ArrayException | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: ArrayException -> SomeException Source # fromException :: SomeException -> Maybe ArrayException Source # displayException :: ArrayException -> String Source #
Exception AssertionFailed | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: AssertionFailed -> SomeException Source # fromException :: SomeException -> Maybe AssertionFailed Source # displayException :: AssertionFailed -> String Source #
Exception AsyncException | Since: base-4.7.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: AsyncException -> SomeException Source # fromException :: SomeException -> Maybe AsyncException Source # displayException :: AsyncException -> String Source #
Exception BlockedIndefinitelyOnMVar | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: BlockedIndefinitelyOnMVar -> SomeException Source # fromException :: SomeException -> Maybe BlockedIndefinitelyOnMVar Source # displayException :: BlockedIndefinitelyOnMVar -> String Source #
Exception BlockedIndefinitelyOnSTM | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: BlockedIndefinitelyOnSTM -> SomeException Source # fromException :: SomeException -> Maybe BlockedIndefinitelyOnSTM Source # displayException :: BlockedIndefinitelyOnSTM -> String Source #
Exception CompactionFailed | Since: base-4.10.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: CompactionFailed -> SomeException Source # fromException :: SomeException -> Maybe CompactionFailed Source # displayException :: CompactionFailed -> String Source #
Exception Deadlock | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: Deadlock -> SomeException Source # fromException :: SomeException -> Maybe Deadlock Source # displayException :: Deadlock -> String Source #
Exception ExitCode | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: ExitCode -> SomeException Source # fromException :: SomeException -> Maybe ExitCode Source # displayException :: ExitCode -> String Source #
Exception FixIOException | Since: base-4.11.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: FixIOException -> SomeException Source # fromException :: SomeException -> Maybe FixIOException Source # displayException :: FixIOException -> String Source #
Exception IOException | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: IOException -> SomeException Source # fromException :: SomeException -> Maybe IOException Source # displayException :: IOException -> String Source #
Exception SomeAsyncException | Since: base-4.7.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: SomeAsyncException -> SomeException Source # fromException :: SomeException -> Maybe SomeAsyncException Source # displayException :: SomeAsyncException -> String Source #
Exception Timeout | Since: base-4.7.0.0
Instance details Defined in System.Timeout Methods toException :: Timeout -> SomeException Source # fromException :: SomeException -> Maybe Timeout Source # displayException :: Timeout -> String Source #

data SomeException Source #

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

Instances details

Exception SomeException | Since: base-3.0
Instance details Defined in GHC.Exception.Type Methods toException :: SomeException -> SomeException Source # fromException :: SomeException -> Maybe SomeException Source # displayException :: SomeException -> String Source #
Show SomeException | Since: base-3.0
Instance details Defined in GHC.Exception.Type Methods showsPrec :: Int -> SomeException -> ShowS Source # show :: SomeException -> String Source # showList :: [SomeException] -> ShowS Source #

data IOException Source #

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

Instances details

Exception IOException | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: IOException -> SomeException Source # fromException :: SomeException -> Maybe IOException Source # displayException :: IOException -> String Source #
Show IOException | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods showsPrec :: Int -> IOException -> ShowS Source # show :: IOException -> String Source # showList :: [IOException] -> ShowS Source #
Eq IOException | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods (==) :: IOException -> IOException -> Bool Source # (/=) :: IOException -> IOException -> Bool Source #
Error IOException |
Instance details Defined in Control.Monad.Trans.Error Methods noMsg :: IOException Source # strMsg :: String -> IOException Source #

data BlockedIndefinitelyOnMVar Source #

The thread is blocked on an `MVar`, but there are no other references to the `MVar` so it can't ever continue.

Constructors

BlockedIndefinitelyOnMVar |

#### Instances

Instances details

Exception BlockedIndefinitelyOnMVar | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: BlockedIndefinitelyOnMVar -> SomeException Source # fromException :: SomeException -> Maybe BlockedIndefinitelyOnMVar Source # displayException :: BlockedIndefinitelyOnMVar -> String Source #
Show BlockedIndefinitelyOnMVar | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods showsPrec :: Int -> BlockedIndefinitelyOnMVar -> ShowS Source # show :: BlockedIndefinitelyOnMVar -> String Source # showList :: [BlockedIndefinitelyOnMVar] -> ShowS Source #

newtype TypeError Source #

An expression that didn't typecheck during compile time was called. This is only possible with -fdefer-type-errors. The `String` gives details about the failed type check.

Since: base-4.9.0.0

Constructors

TypeError String |

#### Instances

Instances details

Exception TypeError | Since: base-4.9.0.0
Instance details Defined in Control.Exception.Base Methods toException :: TypeError -> SomeException Source # fromException :: SomeException -> Maybe TypeError Source # displayException :: TypeError -> String Source #
Show TypeError | Since: base-4.9.0.0
Instance details Defined in Control.Exception.Base Methods showsPrec :: Int -> TypeError -> ShowS Source # show :: TypeError -> String Source # showList :: [TypeError] -> ShowS Source #

data ArithException Source #

Arithmetic exceptions.

Constructors

Overflow |
Underflow |
LossOfPrecision |
DivideByZero |
Denormal |
RatioZeroDenominator | Since: base-4.6.0.0

#### Instances

Instances details

Exception ArithException | Since: base-4.0.0.0
Instance details Defined in GHC.Exception.Type Methods toException :: ArithException -> SomeException Source # fromException :: SomeException -> Maybe ArithException Source # displayException :: ArithException -> String Source #
Show ArithException | Since: base-4.0.0.0
Instance details Defined in GHC.Exception.Type Methods showsPrec :: Int -> ArithException -> ShowS Source # show :: ArithException -> String Source # showList :: [ArithException] -> ShowS Source #
Eq ArithException | Since: base-3.0
Instance details Defined in GHC.Exception.Type Methods (==) :: ArithException -> ArithException -> Bool Source # (/=) :: ArithException -> ArithException -> Bool Source #
Ord ArithException | Since: base-3.0

Instance details

Defined in GHC.Exception.Type

Methods

compare :: ArithException -> ArithException -> Ordering Source #

(<) :: ArithException -> ArithException -> Bool Source #

(<=) :: ArithException -> ArithException -> Bool Source #

(>) :: ArithException -> ArithException -> Bool Source #

(>=) :: ArithException -> ArithException -> Bool Source #

max :: ArithException -> ArithException -> ArithException Source #

min :: ArithException -> ArithException -> ArithException Source #

data ErrorCall Source #

This is thrown when the user calls `error`. The first `String` is the argument given to `error`, second `String` is the location.

Constructors

ErrorCallWithLocation String String |

Bundled Patterns

pattern ErrorCall :: String -> ErrorCall |

#### Instances

Instances details

Exception ErrorCall | Since: base-4.0.0.0
Instance details Defined in GHC.Exception Methods toException :: ErrorCall -> SomeException Source # fromException :: SomeException -> Maybe ErrorCall Source # displayException :: ErrorCall -> String Source #
Show ErrorCall | Since: base-4.0.0.0
Instance details Defined in GHC.Exception Methods showsPrec :: Int -> ErrorCall -> ShowS Source # show :: ErrorCall -> String Source # showList :: [ErrorCall] -> ShowS Source #
Eq ErrorCall | Since: base-4.7.0.0
Instance details Defined in GHC.Exception Methods (==) :: ErrorCall -> ErrorCall -> Bool Source # (/=) :: ErrorCall -> ErrorCall -> Bool Source #
Ord ErrorCall | Since: base-4.7.0.0
Instance details Defined in GHC.Exception Methods compare :: ErrorCall -> ErrorCall -> Ordering Source # (<) :: ErrorCall -> ErrorCall -> Bool Source # (<=) :: ErrorCall -> ErrorCall -> Bool Source # (>) :: ErrorCall -> ErrorCall -> Bool Source # (>=) :: ErrorCall -> ErrorCall -> Bool Source # max :: ErrorCall -> ErrorCall -> ErrorCall Source # min :: ErrorCall -> ErrorCall -> ErrorCall Source #

data MaskingState Source #

Describes the behaviour of a thread when an asynchronous exception is received.

Constructors

Unmasked | asynchronous exceptions are unmasked (the normal state)
MaskedInterruptible | the state during `mask`: asynchronous exceptions are masked, but blocking operations may still be interrupted
MaskedUninterruptible | the state during `uninterruptibleMask`: asynchronous exceptions are masked, and blocking operations may not be interrupted

#### Instances

Instances details

Show MaskingState | Since: base-4.3.0.0
Instance details Defined in GHC.IO Methods showsPrec :: Int -> MaskingState -> ShowS Source # show :: MaskingState -> String Source # showList :: [MaskingState] -> ShowS Source #
Eq MaskingState | Since: base-4.3.0.0
Instance details Defined in GHC.IO Methods (==) :: MaskingState -> MaskingState -> Bool Source # (/=) :: MaskingState -> MaskingState -> Bool Source #

data ArrayException Source #

Exceptions generated by array operations

Constructors

IndexOutOfBounds String | An attempt was made to index an array outside its declared bounds.
UndefinedElement String | An attempt was made to evaluate an element of an array that had not been initialized.

#### Instances

Instances details

Exception ArrayException | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: ArrayException -> SomeException Source # fromException :: SomeException -> Maybe ArrayException Source # displayException :: ArrayException -> String Source #
Show ArrayException | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods showsPrec :: Int -> ArrayException -> ShowS Source # show :: ArrayException -> String Source # showList :: [ArrayException] -> ShowS Source #
Eq ArrayException | Since: base-4.2.0.0
Instance details Defined in GHC.IO.Exception Methods (==) :: ArrayException -> ArrayException -> Bool Source # (/=) :: ArrayException -> ArrayException -> Bool Source #
Ord ArrayException | Since: base-4.2.0.0

Instance details

Defined in GHC.IO.Exception

Methods

compare :: ArrayException -> ArrayException -> Ordering Source #

(<) :: ArrayException -> ArrayException -> Bool Source #

(<=) :: ArrayException -> ArrayException -> Bool Source #

(>) :: ArrayException -> ArrayException -> Bool Source #

(>=) :: ArrayException -> ArrayException -> Bool Source #

max :: ArrayException -> ArrayException -> ArrayException Source #

min :: ArrayException -> ArrayException -> ArrayException Source #

data AsyncException Source #

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:

- It is undefined which thread receives this exception. GHC currently throws this to the same thread that receives `UserInterrupt`, but this may change in the future.
- The GHC RTS currently can only recover from heap overflow if it detects that an explicit memory limit (set via RTS flags). has been exceeded. Currently, failure to allocate memory from the operating system results in immediate termination of the program.

ThreadKilled | This exception is raised by another thread calling `killThread`, or by the system if it needs to terminate the thread for some reason.
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

Instances details

Exception AsyncException | Since: base-4.7.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: AsyncException -> SomeException Source # fromException :: SomeException -> Maybe AsyncException Source # displayException :: AsyncException -> String Source #
Show AsyncException | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods showsPrec :: Int -> AsyncException -> ShowS Source # show :: AsyncException -> String Source # showList :: [AsyncException] -> ShowS Source #
Eq AsyncException | Since: base-4.2.0.0
Instance details Defined in GHC.IO.Exception Methods (==) :: AsyncException -> AsyncException -> Bool Source # (/=) :: AsyncException -> AsyncException -> Bool Source #
Ord AsyncException | Since: base-4.2.0.0

Instance details

Defined in GHC.IO.Exception

Methods

compare :: AsyncException -> AsyncException -> Ordering Source #

(<) :: AsyncException -> AsyncException -> Bool Source #

(<=) :: AsyncException -> AsyncException -> Bool Source #

(>) :: AsyncException -> AsyncException -> Bool Source #

(>=) :: AsyncException -> AsyncException -> Bool Source #

max :: AsyncException -> AsyncException -> AsyncException Source #

min :: AsyncException -> AsyncException -> AsyncException Source #

data SomeAsyncException Source #

Superclass for asynchronous exceptions.

Since: base-4.7.0.0

Constructors

Exception e => SomeAsyncException e |

#### Instances

Instances details

Exception SomeAsyncException | Since: base-4.7.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: SomeAsyncException -> SomeException Source # fromException :: SomeException -> Maybe SomeAsyncException Source # displayException :: SomeAsyncException -> String Source #
Show SomeAsyncException | Since: base-4.7.0.0
Instance details Defined in GHC.IO.Exception Methods showsPrec :: Int -> SomeAsyncException -> ShowS Source # show :: SomeAsyncException -> String Source # showList :: [SomeAsyncException] -> ShowS Source #

newtype CompactionFailed Source #

Compaction found an object that cannot be compacted. Functions cannot be compacted, nor can mutable objects or pinned objects. See `compact`.

Since: base-4.10.0.0

Constructors

CompactionFailed String |

#### Instances

Instances details

Exception CompactionFailed | Since: base-4.10.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: CompactionFailed -> SomeException Source # fromException :: SomeException -> Maybe CompactionFailed Source # displayException :: CompactionFailed -> String Source #
Show CompactionFailed | Since: base-4.10.0.0
Instance details Defined in GHC.IO.Exception Methods showsPrec :: Int -> CompactionFailed -> ShowS Source # show :: CompactionFailed -> String Source # showList :: [CompactionFailed] -> ShowS Source #

data AllocationLimitExceeded Source #

This thread has exceeded its allocation limit. See `setAllocationCounter` and `enableAllocationLimit`.

Since: base-4.8.0.0

Constructors

AllocationLimitExceeded |

#### Instances

Instances details

Exception AllocationLimitExceeded | Since: base-4.8.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: AllocationLimitExceeded -> SomeException Source # fromException :: SomeException -> Maybe AllocationLimitExceeded Source # displayException :: AllocationLimitExceeded -> String Source #
Show AllocationLimitExceeded | Since: base-4.7.1.0
Instance details Defined in GHC.IO.Exception Methods showsPrec :: Int -> AllocationLimitExceeded -> ShowS Source # show :: AllocationLimitExceeded -> String Source # showList :: [AllocationLimitExceeded] -> ShowS Source #

data Deadlock Source #

There are no runnable threads, so the program is deadlocked. The `Deadlock` exception is raised in the main thread only.

Constructors

Deadlock |

#### Instances

Instances details

Exception Deadlock | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: Deadlock -> SomeException Source # fromException :: SomeException -> Maybe Deadlock Source # displayException :: Deadlock -> String Source #
Show Deadlock | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods showsPrec :: Int -> Deadlock -> ShowS Source # show :: Deadlock -> String Source # showList :: [Deadlock] -> ShowS Source #

data BlockedIndefinitelyOnSTM Source #

The thread is waiting to retry an STM transaction, but there are no other references to any `TVar`s involved, so it can't ever continue.

Constructors

BlockedIndefinitelyOnSTM |

#### Instances

Instances details

Exception BlockedIndefinitelyOnSTM | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods toException :: BlockedIndefinitelyOnSTM -> SomeException Source # fromException :: SomeException -> Maybe BlockedIndefinitelyOnSTM Source # displayException :: BlockedIndefinitelyOnSTM -> String Source #
Show BlockedIndefinitelyOnSTM | Since: base-4.1.0.0
Instance details Defined in GHC.IO.Exception Methods showsPrec :: Int -> BlockedIndefinitelyOnSTM -> ShowS Source # show :: BlockedIndefinitelyOnSTM -> String Source # showList :: [BlockedIndefinitelyOnSTM] -> ShowS Source #

data NestedAtomically Source #

Thrown when the program attempts to call `atomically`, from the `stm` package, inside another call to `atomically`.

Constructors

NestedAtomically |

#### Instances

Instances details

Exception NestedAtomically | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: NestedAtomically -> SomeException Source # fromException :: SomeException -> Maybe NestedAtomically Source # displayException :: NestedAtomically -> String Source #
Show NestedAtomically | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods showsPrec :: Int -> NestedAtomically -> ShowS Source # show :: NestedAtomically -> String Source # showList :: [NestedAtomically] -> ShowS Source #

data NonTermination Source #

Thrown when the runtime system detects that the computation is guaranteed not to terminate. Note that there is no guarantee that the runtime system will notice whether any given computation is guaranteed to terminate or not.

Constructors

NonTermination |

#### Instances

Instances details

Exception NonTermination | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: NonTermination -> SomeException Source # fromException :: SomeException -> Maybe NonTermination Source # displayException :: NonTermination -> String Source #
Show NonTermination | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods showsPrec :: Int -> NonTermination -> ShowS Source # show :: NonTermination -> String Source # showList :: [NonTermination] -> ShowS Source #

newtype NoMethodError Source #

A class method without a definition (neither a default definition, nor a definition in the appropriate instance) was called. The `String` gives information about which method it was.

Constructors

NoMethodError String |

#### Instances

Instances details

Exception NoMethodError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: NoMethodError -> SomeException Source # fromException :: SomeException -> Maybe NoMethodError Source # displayException :: NoMethodError -> String Source #
Show NoMethodError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods showsPrec :: Int -> NoMethodError -> ShowS Source # show :: NoMethodError -> String Source # showList :: [NoMethodError] -> ShowS Source #

newtype RecUpdError Source #

A record update was performed on a constructor without the appropriate field. This can only happen with a datatype with multiple constructors, where some fields are in one constructor but not another. The `String` gives information about the source location of the record update.

Constructors

RecUpdError String |

#### Instances

Instances details

Exception RecUpdError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: RecUpdError -> SomeException Source # fromException :: SomeException -> Maybe RecUpdError Source # displayException :: RecUpdError -> String Source #
Show RecUpdError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods showsPrec :: Int -> RecUpdError -> ShowS Source # show :: RecUpdError -> String Source # showList :: [RecUpdError] -> ShowS Source #

newtype RecConError Source #

An uninitialised record field was used. The `String` gives information about the source location where the record was constructed.

Constructors

RecConError String |

#### Instances

Instances details

Exception RecConError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: RecConError -> SomeException Source # fromException :: SomeException -> Maybe RecConError Source # displayException :: RecConError -> String Source #
Show RecConError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods showsPrec :: Int -> RecConError -> ShowS Source # show :: RecConError -> String Source # showList :: [RecConError] -> ShowS Source #

newtype RecSelError Source #

A record selector was applied to a constructor without the appropriate field. This can only happen with a datatype with multiple constructors, where some fields are in one constructor but not another. The `String` gives information about the source location of the record selector.

Constructors

RecSelError String |

#### Instances

Instances details

Exception RecSelError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: RecSelError -> SomeException Source # fromException :: SomeException -> Maybe RecSelError Source # displayException :: RecSelError -> String Source #
Show RecSelError | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods showsPrec :: Int -> RecSelError -> ShowS Source # show :: RecSelError -> String Source # showList :: [RecSelError] -> ShowS Source #

newtype PatternMatchFail Source #

A pattern match failed. The `String` gives information about the source location of the pattern.

Constructors

PatternMatchFail String |

#### Instances

Instances details

Exception PatternMatchFail | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods toException :: PatternMatchFail -> SomeException Source # fromException :: SomeException -> Maybe PatternMatchFail Source # displayException :: PatternMatchFail -> String Source #
Show PatternMatchFail | Since: base-4.0
Instance details Defined in Control.Exception.Base Methods showsPrec :: Int -> PatternMatchFail -> ShowS Source # show :: PatternMatchFail -> String Source # showList :: [PatternMatchFail] -> ShowS Source #

throw :: forall (r :: RuntimeRep) (a :: TYPE r) e. Exception e => e -> a Source #

Throw an exception. Exceptions may be thrown from purely functional code, but may only be caught within the `IO` monad.

WARNING: You may want to use `throwIO` instead so that your pure code stays exception-free.

assert :: Bool -> a -> a Source #

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.

interruptible :: IO a -> IO a Source #

Allow asynchronous exceptions to be raised even inside `mask`, making the operation interruptible (see the discussion of "Interruptible operations" in `Exception`).

When called outside `mask`, or inside `uninterruptibleMask`, this function has no effect.

Since: base-4.9.0.0

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

Since: base-4.7.0.0

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

Since: base-4.7.0.0

mapException :: (Exception e1, Exception e2) => (e1 -> e2) -> a -> a Source #

This function maps one exception into another as proposed in the paper "A semantics for imprecise exceptions".

# Throwing exceptions

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

Generalized version of `throwIO`.

ioError :: MonadBase IO m => IOError -> m a Source #

Generalized version of `ioError`.

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

Generalized version of `throwTo`.

# Catching exceptions

## The `catch` functions

catch Source #

Arguments

:: (MonadBaseControl IO m, Exception e) |
=> m a | The computation to run
-> (e -> m a) | Handler to invoke if an exception is raised
-> m a |

Generalized version of `catch`.

Note, when the given computation throws an exception any monadic side effects in `m` will be discarded.

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

Generalized version of `catches`.

Note, when the given computation throws an exception any monadic side effects in `m` will be discarded.

data Handler m a Source #

Generalized version of `Handler`.

Constructors

forall e.Exception e => Handler (e -> m a) |

catchJust Source #

Arguments

:: (MonadBaseControl IO m, Exception e) |
=> (e -> Maybe b) | Predicate to select exceptions
-> m a | Computation to run
-> (b -> m a) | Handler
-> m a |

Generalized version of `catchJust`.

Note, when the given computation throws an exception any monadic side effects in `m` will be discarded.

## The `handle` functions

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

Generalized version of `handle`.

Note, when the given computation throws an exception any monadic side effects in `m` will be discarded.

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

Generalized version of `handleJust`.

Note, when the given computation throws an exception any monadic side effects in `m` will be discarded.

## The `try` functions

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

Generalized version of `try`.

Note, when the given computation throws an exception any monadic side effects in `m` will be discarded.

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

Generalized version of `tryJust`.

Note, when the given computation throws an exception any monadic side effects in `m` will be discarded.

## The `evaluate` function

evaluate :: MonadBase IO m => a -> m a Source #

Generalized version of `evaluate`.

# Asynchronous Exceptions

## Asynchronous exception control

The following functions allow a thread to control delivery of asynchronous exceptions during a critical region.

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

Generalized version of `mask`.

mask_ :: MonadBaseControl IO m => m a -> m a Source #

Generalized version of `mask_`.

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

Generalized version of `uninterruptibleMask`.

uninterruptibleMask_ :: MonadBaseControl IO m => m a -> m a Source #

Generalized version of `uninterruptibleMask_`.

getMaskingState :: MonadBase IO m => m MaskingState Source #

Generalized version of `getMaskingState`.

allowInterrupt :: MonadBase IO m => m () Source #

Generalized version of `allowInterrupt`.

# Brackets

bracket Source #

Arguments

:: MonadBaseControl IO m |
=> m a | computation to run first ("acquire resource")
-> (a -> m b) | computation to run last ("release resource")
-> (a -> m c) | computation to run in-between
-> m c |

Generalized version of `bracket`.

Note:

- When the "acquire" or "release" computations throw exceptions any monadic side effects in `m` will be discarded.
- When the "in-between" computation throws an exception any monadic side effects in `m` produced by that computation will be discarded but the side effects of the "acquire" or "release" computations will be retained.
- Also, any monadic side effects in `m` of the "release" computation will be discarded; it is run only for its side effects in `IO`.

Note that when your `acquire` and `release` computations are of type `IO` it will be more efficient to write:

    liftBaseOp (bracket acquire release)

bracket_ Source #

Arguments

:: MonadBaseControl IO m |
=> m a | computation to run first ("acquire resource")
-> m b | computation to run last ("release resource")
-> m c | computation to run in-between
-> m c |

Generalized version of `bracket_`.

Note any monadic side effects in `m` of both the "acquire" and "release" computations will be discarded. To keep the monadic side effects of the "acquire" computation, use `bracket` with constant functions instead.

Note that when your `acquire` and `release` computations are of type `IO` it will be more efficient to write:

    liftBaseOp_ (bracket_ acquire release)

bracketOnError Source #

Arguments

:: MonadBaseControl IO m |
=> m a | computation to run first ("acquire resource")
-> (a -> m b) | computation to run last ("release resource")
-> (a -> m c) | computation to run in-between
-> m c |

Generalized version of `bracketOnError`.

Note:

- When the "acquire" or "release" computations throw exceptions any monadic side effects in `m` will be discarded.
- When the "in-between" computation throws an exception any monadic side effects in `m` produced by that computation will be discarded but the side effects of the "acquire" computation will be retained.
- Also, any monadic side effects in `m` of the "release" computation will be discarded; it is run only for its side effects in `IO`.

Note that when your `acquire` and `release` computations are of type `IO` it will be more efficient to write:

    liftBaseOp (bracketOnError acquire release)

# Utilities

finally Source #

Arguments

:: MonadBaseControl IO m |
=> m a | computation to run first
-> m b | computation to run afterward (even if an exception was raised)
-> m a |

Generalized version of `finally`.

Note, any monadic side effects in `m` of the "afterward" computation will be discarded.

onException :: MonadBaseControl IO m => m a -> m b -> m a Source #

Generalized version of `onException`.

Note, any monadic side effects in `m` of the "afterward" computation will be discarded.