Safe Haskell	Safe
Language	Haskell98

UnexceptionalIO

Contents

Unsafe entry points
Pseudo exceptions
Pseudo exception helpers

Description

When you've caught all the exceptions that can be handled safely, this is what you're left with.

runEitherIO . fromIO ≡ id

It is intended that you use qualified imports with this library.

import UnexceptionalIO (UIO)
import qualified UnexceptionalIO as UIO

Synopsis

data UIO a
class Monad m => Unexceptional m where
- lift :: UIO a -> m a
fromIO :: Unexceptional m => IO a -> m (Either SomeNonPseudoException a)
run :: UIO a -> IO a
runEitherIO :: Exception e => UIO (Either e a) -> IO a
fromIO' :: (Exception e, Unexceptional m) => IO a -> m (Either e a)
unsafeFromIO :: Unexceptional m => IO a -> m a
data SomeNonPseudoException
data PseudoException
data ProgrammerError
data ExternalError
bracket :: Unexceptional m => UIO a -> (a -> UIO ()) -> (a -> UIO c) -> m c
forkFinally :: Unexceptional m => UIO a -> (Either PseudoException a -> UIO ()) -> m ThreadId
fork :: Unexceptional m => UIO () -> m ThreadId

Documentation

data UIO a Source #

IO without any PseudoException

Instances

Monad UIO Source #
Instance details Defined in UnexceptionalIO Methods (>>=) :: UIO a -> (a -> UIO b) -> UIO b Source # (>>) :: UIO a -> UIO b -> UIO b Source # return :: a -> UIO a Source # fail :: String -> UIO a Source #
Functor UIO Source #
Instance details Defined in UnexceptionalIO Methods fmap :: (a -> b) -> UIO a -> UIO b Source # (<$) :: a -> UIO b -> UIO a Source #
MonadFix UIO Source #
Instance details Defined in UnexceptionalIO Methods mfix :: (a -> UIO a) -> UIO a Source #
Applicative UIO Source #
Instance details Defined in UnexceptionalIO Methods pure :: a -> UIO a Source # (<>) :: UIO (a -> b) -> UIO a -> UIO b Source # liftA2 :: (a -> b -> c) -> UIO a -> UIO b -> UIO c Source # (>) :: UIO a -> UIO b -> UIO b Source # (<*) :: UIO a -> UIO b -> UIO a Source #
Unexceptional UIO Source #
Instance details Defined in UnexceptionalIO Methods lift :: UIO a -> UIO a Source #

class Monad m => Unexceptional m where Source #

Polymorphic base without any PseudoException

Methods

lift :: UIO a -> m a Source #

Instances

Unexceptional IO Source #
Instance details Defined in UnexceptionalIO Methods lift :: UIO a -> IO a Source #
Unexceptional UIO Source #
Instance details Defined in UnexceptionalIO Methods lift :: UIO a -> UIO a Source #

fromIO :: Unexceptional m => IO a -> m (Either SomeNonPseudoException a) Source #

Catch any exception but PseudoException in an IO action

run :: UIO a -> IO a Source #

Re-embed UIO into IO

runEitherIO :: Exception e => UIO (Either e a) -> IO a Source #

Re-embed UIO and possible exception back into IO

Unsafe entry points

fromIO' :: (Exception e, Unexceptional m) => IO a -> m (Either e a) Source #

You promise that e covers all exceptions but PseudoException thrown by this IO action

This function is partial if you lie

unsafeFromIO :: Unexceptional m => IO a -> m a Source #

You promise there are no exceptions but PseudoException thrown by this IO action

Pseudo exceptions

data SomeNonPseudoException Source #

Every SomeException but PseudoException

Instances

Show SomeNonPseudoException Source #
Instance details Defined in UnexceptionalIO Methods showsPrec :: Int -> SomeNonPseudoException -> ShowS Source # show :: SomeNonPseudoException -> String Source # showList :: [SomeNonPseudoException] -> ShowS Source #
Exception SomeNonPseudoException Source #
Instance details Defined in UnexceptionalIO Methods toException :: SomeNonPseudoException -> SomeException Source # fromException :: SomeException -> Maybe SomeNonPseudoException Source # displayException :: SomeNonPseudoException -> String Source #

data PseudoException Source #

Not everything handled by the exception system is a run-time error you can handle. This is the class of pseudo-exceptions you usually can do nothing about, just log or exit.

Additionally, except for ExitCode any of these psuedo-exceptions you could never guarentee to have caught, since they can come from anywhere at any time, we could never guarentee that UIO does not contain them.

Constructors

ProgrammerError ProgrammerError	Mistakes programmers make
ExternalError ExternalError	Errors thrown by the runtime
Exit ExitCode	Process exit requests

Instances

Show PseudoException Source #
Instance details Defined in UnexceptionalIO Methods showsPrec :: Int -> PseudoException -> ShowS Source # show :: PseudoException -> String Source # showList :: [PseudoException] -> ShowS Source #
Exception PseudoException Source #
Instance details Defined in UnexceptionalIO Methods toException :: PseudoException -> SomeException Source # fromException :: SomeException -> Maybe PseudoException Source # displayException :: PseudoException -> String Source #

data ProgrammerError Source #

Pseudo-exceptions caused by a programming error

Partial functions, error, undefined, etc

Instances

Show ProgrammerError Source #
Instance details Defined in UnexceptionalIO Methods showsPrec :: Int -> ProgrammerError -> ShowS Source # show :: ProgrammerError -> String Source # showList :: [ProgrammerError] -> ShowS Source #
Exception ProgrammerError Source #
Instance details Defined in UnexceptionalIO Methods toException :: ProgrammerError -> SomeException Source # fromException :: SomeException -> Maybe ProgrammerError Source # displayException :: ProgrammerError -> String Source #

data ExternalError Source #

Pseudo-exceptions thrown by the runtime environment

Constructors

CompactionFailed CompactionFailed
FixIOException FixIOException
AsyncException SomeAsyncException
BlockedIndefinitelyOnSTM BlockedIndefinitelyOnSTM
BlockedIndefinitelyOnMVar BlockedIndefinitelyOnMVar
Deadlock Deadlock
NonTermination NonTermination

Instances

Show ExternalError Source #
Instance details Defined in UnexceptionalIO Methods showsPrec :: Int -> ExternalError -> ShowS Source # show :: ExternalError -> String Source # showList :: [ExternalError] -> ShowS Source #
Exception ExternalError Source #
Instance details Defined in UnexceptionalIO Methods toException :: ExternalError -> SomeException Source # fromException :: SomeException -> Maybe ExternalError Source # displayException :: ExternalError -> String Source #

Pseudo exception helpers

bracket :: Unexceptional m => UIO a -> (a -> UIO ()) -> (a -> UIO c) -> m c Source #

When you're doing resource handling, PseudoException matters. You still need to use the bracket pattern to handle cleanup.

forkFinally :: Unexceptional m => UIO a -> (Either PseudoException a -> UIO ()) -> m ThreadId Source #

Mirrors forkFinally, but since the body is UIO, the thread must terminate successfully or because of PseudoException

fork :: Unexceptional m => UIO () -> m ThreadId Source #

Mirrors forkIO, but re-throws any PseudoException to the parent thread

TypeError TypeError
ArithException ArithException
ArrayException ArrayException
AssertionFailed AssertionFailed
ErrorCall ErrorCall
NestedAtomically NestedAtomically
NoMethodError NoMethodError
PatternMatchFail PatternMatchFail
RecConError RecConError
RecSelError RecSelError
RecUpdError RecSelError