Safe Haskell	Safe-Inferred
Language	Haskell2010

Haxl.Core.Exception

Contents

Exception categories
Exception utilities

Description

An exception hierarchy that can be used with the Haxl monad.

The Haxl framework may throw exceptions from this hierarchy: for example, a misbehaving data source causes dataFetch to throw a DataSourceError. The combinator withDefault from Haxl.Core.Prelude uses this hierarchy to provide default values for expressions that raise TransientError or LogicError exceptions.

You are under no obligations to use this hierarchy for your own exceptions, but you might find it useful nonetheless; for withDefault to be useful, for example, you'll want your exceptions to be children of LogicError or TransientError as appropriate.

Most users should import Haxl.Core instead of importing this module directly.

Synopsis

data HaxlException = forall e.MiddleException e => HaxlException (Maybe Stack) e
data InternalError = forall e.Exception e => InternalError e
internalErrorToException :: Exception e => e -> SomeException
internalErrorFromException :: Exception e => SomeException -> Maybe e
data LogicError = forall e.Exception e => LogicError e
logicErrorToException :: Exception e => e -> SomeException
logicErrorFromException :: Exception e => SomeException -> Maybe e
data LogicBug = forall e.Exception e => LogicBug e
logicBugToException :: Exception e => e -> SomeException
logicBugFromException :: Exception e => SomeException -> Maybe e
data TransientError = forall e.Exception e => TransientError e
transientErrorToException :: Exception e => e -> SomeException
transientErrorFromException :: Exception e => SomeException -> Maybe e
newtype CriticalError = CriticalError Text
newtype DataSourceError = DataSourceError Text
newtype NonHaxlException = NonHaxlException Text
newtype NotFound = NotFound Text
newtype UnexpectedType = UnexpectedType Text
newtype EmptyList = EmptyList Text
newtype JSONError = JSONError Text
newtype InvalidParameter = InvalidParameter Text
newtype MonadFail = MonadFail Text
newtype FetchError = FetchError Text
asHaxlException :: SomeException -> HaxlException
class Exception a => MiddleException a where
- eName :: a -> String
rethrowAsyncExceptions :: SomeException -> IO ()
tryWithRethrow :: IO a -> IO (Either SomeException a)

Documentation

data HaxlException Source #

We have a 3-tiered hierarchy of exceptions, with HaxlException at the top, and all Haxl exceptions as children of this. Users should never deal directly with HaxlExceptions.

The main types of exceptions are:

InternalError: Something is wrong with Haxl core.
LogicBug: Something is wrong with Haxl client code.
LogicError: Things that really should be return values, e.g. NotFound.
TransientError: Something is temporarily failing (usually in a fetch).

These are not meant to be thrown (but likely be caught). Thrown exceptions should be a subclass of one of these. There are some generic leaf exceptions defined below this, such as FetchError (generic transient failure) or CriticalError (internal failure).

Constructors

forall e.MiddleException e => HaxlException (Maybe Stack) e

Instances

Instances details

ToJSON HaxlException Source #	These need to be serializable to JSON to cross FFI boundaries.
Instance details Defined in Haxl.Core.Exception Methods toJSON :: HaxlException -> Value # toEncoding :: HaxlException -> Encoding # toJSONList :: [HaxlException] -> Value # toEncodingList :: [HaxlException] -> Encoding # omitField :: HaxlException -> Bool #
Exception HaxlException Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: HaxlException -> SomeException # fromException :: SomeException -> Maybe HaxlException # displayException :: HaxlException -> String #
Show HaxlException Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> HaxlException -> ShowS # show :: HaxlException -> String # showList :: [HaxlException] -> ShowS #

Exception categories

data InternalError Source #

For errors in Haxl core code.

Constructors

forall e.Exception e => InternalError e

Instances

Instances details

Exception InternalError Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: InternalError -> SomeException # fromException :: SomeException -> Maybe InternalError # displayException :: InternalError -> String #
Show InternalError Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> InternalError -> ShowS # show :: InternalError -> String # showList :: [InternalError] -> ShowS #
MiddleException InternalError Source #
Instance details Defined in Haxl.Core.Exception Methods eName :: InternalError -> String Source #

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

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

data LogicError Source #

For errors in Haxl client code.

Constructors

forall e.Exception e => LogicError e

Instances

Instances details

Exception LogicError Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: LogicError -> SomeException # fromException :: SomeException -> Maybe LogicError # displayException :: LogicError -> String #
Show LogicError Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> LogicError -> ShowS # show :: LogicError -> String # showList :: [LogicError] -> ShowS #
MiddleException LogicError Source #
Instance details Defined in Haxl.Core.Exception Methods eName :: LogicError -> String Source #

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

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

data LogicBug Source #

Constructors

forall e.Exception e => LogicBug e

Instances

Instances details

Exception LogicBug Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: LogicBug -> SomeException # fromException :: SomeException -> Maybe LogicBug # displayException :: LogicBug -> String #
Show LogicBug Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> LogicBug -> ShowS # show :: LogicBug -> String # showList :: [LogicBug] -> ShowS #
MiddleException LogicBug Source #
Instance details Defined in Haxl.Core.Exception Methods eName :: LogicBug -> String Source #

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

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

data TransientError Source #

For transient failures.

Constructors

forall e.Exception e => TransientError e

Instances

Instances details

Exception TransientError Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: TransientError -> SomeException # fromException :: SomeException -> Maybe TransientError # displayException :: TransientError -> String #
Show TransientError Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> TransientError -> ShowS # show :: TransientError -> String # showList :: [TransientError] -> ShowS #
MiddleException TransientError Source #
Instance details Defined in Haxl.Core.Exception Methods eName :: TransientError -> String Source #

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

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

Internal exceptions

newtype CriticalError Source #

Generic "critical" exception. Something internal is borked. Panic.

Constructors

CriticalError Text

Instances

Instances details

Exception CriticalError Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: CriticalError -> SomeException # fromException :: SomeException -> Maybe CriticalError # displayException :: CriticalError -> String #
Show CriticalError Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> CriticalError -> ShowS # show :: CriticalError -> String # showList :: [CriticalError] -> ShowS #
Binary CriticalError Source #
Instance details Defined in Haxl.Core.Exception Methods put :: CriticalError -> Put # get :: Get CriticalError # putList :: [CriticalError] -> Put #
Eq CriticalError Source #
Instance details Defined in Haxl.Core.Exception Methods (==) :: CriticalError -> CriticalError -> Bool # (/=) :: CriticalError -> CriticalError -> Bool #

newtype DataSourceError Source #

A data source did something wrong

Constructors

DataSourceError Text

Instances

Instances details

Exception DataSourceError Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: DataSourceError -> SomeException # fromException :: SomeException -> Maybe DataSourceError # displayException :: DataSourceError -> String #
Show DataSourceError Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> DataSourceError -> ShowS # show :: DataSourceError -> String # showList :: [DataSourceError] -> ShowS #
Eq DataSourceError Source #
Instance details Defined in Haxl.Core.Exception Methods (==) :: DataSourceError -> DataSourceError -> Bool # (/=) :: DataSourceError -> DataSourceError -> Bool #

newtype NonHaxlException Source #

Exceptions that are converted to HaxlException by asHaxlException. Typically these will be pure exceptions, e.g., the error function in pure code, or a pattern-match failure.

Constructors

NonHaxlException Text

Instances

Instances details

Exception NonHaxlException Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: NonHaxlException -> SomeException # fromException :: SomeException -> Maybe NonHaxlException # displayException :: NonHaxlException -> String #
Show NonHaxlException Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> NonHaxlException -> ShowS # show :: NonHaxlException -> String # showList :: [NonHaxlException] -> ShowS #
Binary NonHaxlException Source #
Instance details Defined in Haxl.Core.Exception Methods put :: NonHaxlException -> Put # get :: Get NonHaxlException # putList :: [NonHaxlException] -> Put #
Eq NonHaxlException Source #
Instance details Defined in Haxl.Core.Exception Methods (==) :: NonHaxlException -> NonHaxlException -> Bool # (/=) :: NonHaxlException -> NonHaxlException -> Bool #

Logic exceptions

newtype NotFound Source #

Generic "something was not found" exception.

Constructors

NotFound Text

Instances

Instances details

Exception NotFound Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: NotFound -> SomeException # fromException :: SomeException -> Maybe NotFound # displayException :: NotFound -> String #
Show NotFound Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> NotFound -> ShowS # show :: NotFound -> String # showList :: [NotFound] -> ShowS #
Binary NotFound Source #
Instance details Defined in Haxl.Core.Exception Methods put :: NotFound -> Put # get :: Get NotFound # putList :: [NotFound] -> Put #
Eq NotFound Source #
Instance details Defined in Haxl.Core.Exception Methods (==) :: NotFound -> NotFound -> Bool # (/=) :: NotFound -> NotFound -> Bool #

newtype UnexpectedType Source #

Generic "something had the wrong type" exception.

Constructors

UnexpectedType Text

Instances

Instances details

Exception UnexpectedType Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: UnexpectedType -> SomeException # fromException :: SomeException -> Maybe UnexpectedType # displayException :: UnexpectedType -> String #
Show UnexpectedType Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> UnexpectedType -> ShowS # show :: UnexpectedType -> String # showList :: [UnexpectedType] -> ShowS #
Eq UnexpectedType Source #
Instance details Defined in Haxl.Core.Exception Methods (==) :: UnexpectedType -> UnexpectedType -> Bool # (/=) :: UnexpectedType -> UnexpectedType -> Bool #

newtype EmptyList Source #

Generic "input list was empty" exception.

Constructors

EmptyList Text

Instances

Instances details

Exception EmptyList Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: EmptyList -> SomeException # fromException :: SomeException -> Maybe EmptyList # displayException :: EmptyList -> String #
Show EmptyList Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> EmptyList -> ShowS # show :: EmptyList -> String # showList :: [EmptyList] -> ShowS #
Eq EmptyList Source #
Instance details Defined in Haxl.Core.Exception Methods (==) :: EmptyList -> EmptyList -> Bool # (/=) :: EmptyList -> EmptyList -> Bool #

newtype JSONError Source #

Generic "Incorrect assumptions about JSON data" exception.

Constructors

JSONError Text

Instances

Instances details

Exception JSONError Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: JSONError -> SomeException # fromException :: SomeException -> Maybe JSONError # displayException :: JSONError -> String #
Show JSONError Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> JSONError -> ShowS # show :: JSONError -> String # showList :: [JSONError] -> ShowS #
Eq JSONError Source #
Instance details Defined in Haxl.Core.Exception Methods (==) :: JSONError -> JSONError -> Bool # (/=) :: JSONError -> JSONError -> Bool #

newtype InvalidParameter Source #

Generic "passing some invalid parameter" exception.

Constructors

InvalidParameter Text

Instances

Instances details

Exception InvalidParameter Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: InvalidParameter -> SomeException # fromException :: SomeException -> Maybe InvalidParameter # displayException :: InvalidParameter -> String #
Show InvalidParameter Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> InvalidParameter -> ShowS # show :: InvalidParameter -> String # showList :: [InvalidParameter] -> ShowS #
Eq InvalidParameter Source #
Instance details Defined in Haxl.Core.Exception Methods (==) :: InvalidParameter -> InvalidParameter -> Bool # (/=) :: InvalidParameter -> InvalidParameter -> Bool #

newtype MonadFail Source #

Generic "fail was called" exception.

Constructors

MonadFail Text

Instances

Instances details

Exception MonadFail Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: MonadFail -> SomeException # fromException :: SomeException -> Maybe MonadFail # displayException :: MonadFail -> String #
Show MonadFail Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> MonadFail -> ShowS # show :: MonadFail -> String # showList :: [MonadFail] -> ShowS #
Eq MonadFail Source #
Instance details Defined in Haxl.Core.Exception Methods (==) :: MonadFail -> MonadFail -> Bool # (/=) :: MonadFail -> MonadFail -> Bool #

Transient exceptions

newtype FetchError Source #

Generic transient fetching exceptions.

Constructors

FetchError Text

Instances

Instances details

Exception FetchError Source #
Instance details Defined in Haxl.Core.Exception Methods toException :: FetchError -> SomeException # fromException :: SomeException -> Maybe FetchError # displayException :: FetchError -> String #
Show FetchError Source #
Instance details Defined in Haxl.Core.Exception Methods showsPrec :: Int -> FetchError -> ShowS # show :: FetchError -> String # showList :: [FetchError] -> ShowS #
Eq FetchError Source #
Instance details Defined in Haxl.Core.Exception Methods (==) :: FetchError -> FetchError -> Bool # (/=) :: FetchError -> FetchError -> Bool #

Exception utilities

asHaxlException :: SomeException -> HaxlException Source #

Converts all exceptions that are not derived from HaxlException into NonHaxlException, using show.

class Exception a => MiddleException a where Source #

Methods

eName :: a -> String Source #

Instances

Instances details

MiddleException InternalError Source #
Instance details Defined in Haxl.Core.Exception Methods eName :: InternalError -> String Source #
MiddleException LogicBug Source #
Instance details Defined in Haxl.Core.Exception Methods eName :: LogicBug -> String Source #
MiddleException LogicError Source #
Instance details Defined in Haxl.Core.Exception Methods eName :: LogicError -> String Source #
MiddleException TransientError Source #
Instance details Defined in Haxl.Core.Exception Methods eName :: TransientError -> String Source #

rethrowAsyncExceptions :: SomeException -> IO () Source #

tryWithRethrow :: IO a -> IO (Either SomeException a) Source #