fused-effects-exceptions-1.0.0.0: Handle exceptions thrown in IO with fused-effects.

Control.Effect.Exception

Contents

Description

Operations from Control.Exception lifted into effectful contexts using Lift.

Since: 1.0.0.0

Synopsis

# Lifted Control.Exception operations

throwIO :: (Exception e, Has (Lift IO) sig m) => e -> m a Source #

See Control.Exception.throwIO.

Since: 1.0.0.0

ioError :: Has (Lift IO) sig m => IOError -> m a Source #

See Control.Exception.ioError.

Since: 1.0.0.0

throwTo :: (Exception e, Has (Lift IO) sig m) => ThreadId -> e -> m () Source #

See Control.Exception.throwTo.

Since: 1.0.0.0

catch :: (Exception e, Has (Lift IO) sig m) => m a -> (e -> m a) -> m a Source #

See Control.Exception.catch.

Since: 1.0.0.0

catches :: Has (Lift IO) sig m => m a -> [Handler m a] -> m a Source #

See Control.Exception.catches.

Since: 1.0.0.0

data Handler m a Source #

See Control.Exception.Handler.

Since: 1.0.0.0

Constructors

 Exception e => Handler (e -> m a)
Instances
 Functor m => Functor (Handler m) Source # Instance detailsDefined in Control.Effect.Exception Methodsfmap :: (a -> b) -> Handler m a -> Handler m b #(<$) :: a -> Handler m b -> Handler m a # catchJust :: (Exception e, Has (Lift IO) sig m) => (e -> Maybe b) -> m a -> (b -> m a) -> m a Source # See Control.Exception.catchJust. Since: 1.0.0.0 handle :: (Exception e, Has (Lift IO) sig m) => (e -> m a) -> m a -> m a Source # See Control.Exception.handle. Since: 1.0.0.0 handleJust :: (Exception e, Has (Lift IO) sig m) => (e -> Maybe b) -> (b -> m a) -> m a -> m a Source # See Control.Exception.handleJust. Since: 1.0.0.0 try :: (Exception e, Has (Lift IO) sig m) => m a -> m (Either e a) Source # See Control.Exception.try. Since: 1.0.0.0 tryJust :: (Exception e, Has (Lift IO) sig m) => (e -> Maybe b) -> m a -> m (Either b a) Source # See Control.Exception.tryJust. Since: 1.0.0.0 evaluate :: Has (Lift IO) sig m => a -> m a Source # See Control.Exception.evaluate. Since: 1.0.0.0 mask :: Has (Lift IO) sig m => ((forall a. m a -> m a) -> m b) -> m b Source # See Control.Exception.mask. Since: 1.0.0.0 mask_ :: Has (Lift IO) sig m => m a -> m a Source # See Control.Exception.mask_. Since: 1.0.0.0 uninterruptibleMask :: Has (Lift IO) sig m => ((forall a. m a -> m a) -> m b) -> m b Source # See Control.Exception.uninterruptibleMask. Since: 1.0.0.0 uninterruptibleMask_ :: Has (Lift IO) sig m => m a -> m a Source # See Control.Exception.uninterruptibleMask_. Since: 1.0.0.0 getMaskingState :: Has (Lift IO) sig m => m MaskingState Source # See Control.Exception.getMaskingState. Since: 1.0.0.0 interruptible :: Has (Lift IO) sig m => m a -> m a Source # See Control.Exception.interruptible. Since: 1.0.0.0 allowInterrupt :: Has (Lift IO) sig m => m () Source # See Control.Exception.allowInterrupt. Since: 1.0.0.0 bracket :: Has (Lift IO) sig m => m a -> (a -> m b) -> (a -> m c) -> m c Source # See Control.Exception.bracket. Since: 1.0.0.0 bracket_ :: Has (Lift IO) sig m => m a -> m b -> m c -> m c Source # See Control.Exception.bracket_. Since: 1.0.0.0 bracketOnError :: Has (Lift IO) sig m => m a -> (a -> m b) -> (a -> m c) -> m c Source # See Control.Exception.bracketOnError. Since: 1.0.0.0 finally :: Has (Lift IO) sig m => m a -> m b -> m a Source # See Control.Exception.finally. Since: 1.0.0.0 onException :: Has (Lift IO) sig m => m a -> m b -> m a Source # See Control.Exception.onException. Since: 1.0.0.0 assert :: Bool -> a -> a # 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. mapException :: (Exception e1, Exception e2) => (e1 -> e2) -> a -> a # This function maps one exception into another as proposed in the paper "A semantics for imprecise exceptions". newtype PatternMatchFail # A pattern match failed. The String gives information about the source location of the pattern. Constructors  PatternMatchFail String Instances  Since: base-4.0 Instance detailsDefined in Control.Exception.Base MethodsshowList :: [PatternMatchFail] -> ShowS # Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods newtype RecSelError # 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  Since: base-4.0 Instance detailsDefined in Control.Exception.Base MethodsshowList :: [RecSelError] -> ShowS # Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods newtype RecConError # An uninitialised record field was used. The String gives information about the source location where the record was constructed. Constructors  RecConError String Instances  Since: base-4.0 Instance detailsDefined in Control.Exception.Base MethodsshowList :: [RecConError] -> ShowS # Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods newtype RecUpdError # 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  Since: base-4.0 Instance detailsDefined in Control.Exception.Base MethodsshowList :: [RecUpdError] -> ShowS # Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods newtype NoMethodError # 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  Since: base-4.0 Instance detailsDefined in Control.Exception.Base MethodsshowList :: [NoMethodError] -> ShowS # Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods newtype TypeError # 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  Since: base-4.9.0.0 Instance detailsDefined in Control.Exception.Base MethodsshowList :: [TypeError] -> ShowS # Since: base-4.9.0.0 Instance detailsDefined in Control.Exception.Base Methods data NonTermination # 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  Since: base-4.0 Instance detailsDefined in Control.Exception.Base MethodsshowList :: [NonTermination] -> ShowS # Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods Thrown when the program attempts to call atomically, from the stm package, inside another call to atomically. Constructors  NestedAtomically Instances  Since: base-4.0 Instance detailsDefined in Control.Exception.Base MethodsshowList :: [NestedAtomically] -> ShowS # Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods Since: base-4.7.0.0 Since: base-4.7.0.0 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  Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception The thread is waiting to retry an STM transaction, but there are no other references to any TVars involved, so it can't ever continue. Constructors  BlockedIndefinitelyOnSTM Instances  Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception data Deadlock # There are no runnable threads, so the program is deadlocked. The Deadlock exception is raised in the main thread only. Constructors  Deadlock Instances  Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception MethodsshowList :: [Deadlock] -> ShowS # Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods This thread has exceeded its allocation limit. See setAllocationCounter and enableAllocationLimit. Since: base-4.8.0.0 Constructors  AllocationLimitExceeded Instances  Since: base-4.7.1.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.8.0.0 Instance detailsDefined in GHC.IO.Exception newtype CompactionFailed # 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  Since: base-4.10.0.0 Instance detailsDefined in GHC.IO.Exception MethodsshowList :: [CompactionFailed] -> ShowS # Since: base-4.10.0.0 Instance detailsDefined in GHC.IO.Exception Methods newtype AssertionFailed # assert was applied to False. Constructors  AssertionFailed String Instances  Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception MethodsshowList :: [AssertionFailed] -> ShowS # Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods data SomeAsyncException where # Superclass for asynchronous exceptions. Since: base-4.7.0.0 Constructors  SomeAsyncException :: forall e. Exception e => e -> SomeAsyncException Instances  Since: base-4.7.0.0 Instance detailsDefined in GHC.IO.Exception MethodsshowList :: [SomeAsyncException] -> ShowS # Since: base-4.7.0.0 Instance detailsDefined in GHC.IO.Exception Methods 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: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  Since: base-4.2.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.2.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception MethodsshowList :: [AsyncException] -> ShowS # Since: base-4.7.0.0 Instance detailsDefined in GHC.IO.Exception Methods data ArrayException # 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  Since: base-4.2.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.2.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception MethodsshowList :: [ArrayException] -> ShowS # Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods data MaskingState # 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  Since: base-4.3.0.0 Instance detailsDefined in GHC.IO Methods Since: base-4.3.0.0 Instance detailsDefined in GHC.IO MethodsshowList :: [MaskingState] -> ShowS # 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  Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception MethodsshowList :: [IOException] -> ShowS # Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods throw :: Exception e => e -> a # Throw an exception. Exceptions may be thrown from purely functional code, but may only be caught within the IO monad. data ErrorCall # 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  Since: base-4.7.0.0 Instance detailsDefined in GHC.Exception Methods Since: base-4.7.0.0 Instance detailsDefined in GHC.Exception Methods Since: base-4.0.0.0 Instance detailsDefined in GHC.Exception MethodsshowList :: [ErrorCall] -> ShowS # Since: base-4.0.0.0 Instance detailsDefined in GHC.Exception Methods 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 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 # displayException :: e -> String # Render this exception value in a human-friendly manner. Default implementation: show. Since: base-4.8.0.0 Instances  Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods Since: base-4.9.0.0 Instance detailsDefined in Control.Exception.Base Methods Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods Since: base-4.0 Instance detailsDefined in Control.Exception.Base Methods Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.8.0.0 Instance detailsDefined in GHC.IO.Exception Since: base-4.10.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.7.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.7.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.11.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.1.0.0 Instance detailsDefined in GHC.IO.Exception Methods Since: base-4.0.0.0 Instance detailsDefined in GHC.Exception Methods Since: base-4.0.0.0 Instance detailsDefined in GHC.Exception.Type Methods Since: base-3.0 Instance detailsDefined in GHC.Exception.Type Methods data ArithException # Arithmetic exceptions. Constructors  Overflow Underflow LossOfPrecision DivideByZero Denormal RatioZeroDenominator Since: base-4.6.0.0 Instances  Since: base-3.0 Instance detailsDefined in GHC.Exception.Type Methods Since: base-3.0 Instance detailsDefined in GHC.Exception.Type Methods Since: base-4.0.0.0 Instance detailsDefined in GHC.Exception.Type MethodsshowList :: [ArithException] -> ShowS # Since: base-4.0.0.0 Instance detailsDefined in GHC.Exception.Type Methods data SomeException where # 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  SomeException :: forall e. Exception e => e -> SomeException Instances  Since: base-3.0 Instance detailsDefined in GHC.Exception.Type MethodsshowList :: [SomeException] -> ShowS # Since: base-3.0 Instance detailsDefined in GHC.Exception.Type Methods # Lift effect data Lift (sig :: Type -> Type) (m :: Type -> Type) k where # Since: fused-effects-1.0.0.0 Constructors  LiftWith :: forall (sig :: Type -> Type) (m :: Type -> Type) k a. (forall (ctx :: Type -> Type). Functor ctx => ctx () -> (forall a1. ctx (m a1) -> sig (ctx a1)) -> sig (ctx a)) -> (a -> m k) -> Lift sig m k Instances  HFunctor (Lift sig) Instance detailsDefined in Control.Effect.Lift.Internal Methodshmap :: Functor m => (forall x. m x -> n x) -> Lift sig m a -> Lift sig n a # Functor sig => Effect (Lift sig) Instance detailsDefined in Control.Effect.Lift.Internal Methodsthread :: (Functor ctx, Monad m) => ctx () -> (forall x. ctx (m x) -> n (ctx x)) -> Lift sig m a -> Lift sig n (ctx a) # Instance detailsDefined in Control.Algebra Methodsalg :: Lift IO IO a -> IO a # Instance detailsDefined in Control.Algebra Methods Functor m => Functor (Lift sig m) Instance detailsDefined in Control.Effect.Lift.Internal Methodsfmap :: (a -> b) -> Lift sig m a -> Lift sig m b #(<$) :: a -> Lift sig m b -> Lift sig m a #

sendM :: (Has (Lift n) sig m, Functor n) => n a -> m a #

Given a Lift n constraint in a signature carried by m, sendM promotes arbitrary actions of type n a to m a. It is spiritually similar to lift from the MonadTrans typeclass.

Since: fused-effects-1.0.0.0

liftWith :: Has (Lift n) sig m => (forall (ctx :: Type -> Type). Functor ctx => ctx () -> (forall a1. ctx (m a1) -> n (ctx a1)) -> n (ctx a)) -> m a #

Run actions in an outer context.

This can be used to provide interoperation with base functionality like Control.Exception.catch:

liftWith $ctx hdl -> catch (hdl (m <$ ctx)) (hdl . (<\$ ctx) . h)


The higher-order function takes both an initial context, and a handler phrased as the same sort of distributive law as described in the documentation for thread. This handler takes actions lifted into a context functor, which can be either the initial context, or the derived context produced by handling a previous action.

As with MonadBaseControl, care must be taken when lifting functions like Control.Exception.finally which don’t use the return value of one of their actions, as this can lead to dropped effects.

Since: fused-effects-1.0.0.0

# Re-exports

class (HFunctor sig, Monad m) => Algebra (sig :: (Type -> Type) -> Type -> Type) (m :: Type -> Type) | m -> sig #

The class of carriers (results) for algebras (effect handlers) over signatures (effects), whose actions are given by the alg method.

Since: fused-effects-1.0.0.0

Minimal complete definition

alg

Instances

type Has (eff :: (Type -> Type) -> Type -> Type) (sig :: (Type -> Type) -> Type -> Type) (m :: Type -> Type) = (Members eff sig, Algebra sig m) #

m is a carrier for sig containing eff.

Note that if eff is a sum, it will be decomposed into multiple Member constraints. While this technically allows one to combine multiple unrelated effects into a single Has constraint, doing so has two significant drawbacks:

1. Due to a problem with recursive type families, this can lead to significantly slower compiles.
2. It defeats ghc’s warnings for redundant constraints, and thus can lead to a proliferation of redundant constraints as code is changed.

run :: Identity a -> a #

Run an action exhausted of effects to produce its final result value.

Since: fused-effects-1.0.0.0