Safe Haskell	None
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 = MiddleException e => HaxlException (Maybe Stack) e
data InternalError = Exception e => InternalError e
internalErrorToException :: Exception e => e -> SomeException
internalErrorFromException :: Exception e => SomeException -> Maybe e
data LogicError = Exception e => LogicError e
logicErrorToException :: Exception e => e -> SomeException
logicErrorFromException :: Exception e => SomeException -> Maybe e
data LogicBug = Exception e => LogicBug e
logicBugToException :: Exception e => e -> SomeException
logicBugFromException :: Exception e => SomeException -> Maybe e
data TransientError = 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

MiddleException e => HaxlException (Maybe Stack) e

Instances

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

Exception categories

data InternalError Source #

For errors in Haxl core code.

Constructors

Exception e => InternalError e

Instances

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

Exception e => LogicError e

Instances

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

Exception e => LogicBug e

Instances

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

Exception e => TransientError e

Instances

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

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

newtype DataSourceError Source #

A data source did something wrong

Constructors

DataSourceError Text

Instances

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

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

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

Logic exceptions

newtype NotFound Source #

Generic "something was not found" exception.

Constructors

NotFound Text

Instances

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

newtype UnexpectedType Source #

Generic "something had the wrong type" exception.

Constructors

UnexpectedType Text

Instances

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

newtype EmptyList Source #

Generic "input list was empty" exception.

Constructors

EmptyList Text

Instances

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

newtype JSONError Source #

Generic "Incorrect assumptions about JSON data" exception.

Constructors

JSONError Text

Instances

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

newtype InvalidParameter Source #

Generic "passing some invalid parameter" exception.

Constructors

InvalidParameter Text

Instances

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

newtype MonadFail Source #

Generic "fail was called" exception.

Constructors

MonadFail Text

Instances

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

Transient exceptions

newtype FetchError Source #

Generic transient fetching exceptions.

Constructors

FetchError Text

Instances

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

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

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 InternalError Source #
Instance details Defined in Haxl.Core.Exception Methods eName :: InternalError -> 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 #