Moduleextensible-effects-5.0.0.1Haskell2010

Control.Eff.Exception

Exception-producing and exception-handling effects

2 types
15 values

Packageextensible-effects-5.0.0.1
Exports17
LanguageHaskell2010
LicenceMIT
SourceException.hs

newtypenewtype Exc e (v :: k)

Exceptions

exceptions of the type e; no resumption

Constructors

Exc e

Instances3MonadBaseControl, Handle, StM

(MonadBase m m, LiftedBase m r) => MonadBaseControl m (Eff (Exc e ': r))Defined in extensible-effects-5.0.0.1 · Control.Eff.Exception
Monad m => Handle (Exc e) r a (m (Either e a))Defined in extensible-effects-5.0.0.1 · Control.Eff.Exception
Given a callback, and an Exc request, respond to it.
type StM (Eff (Exc e ': r)) a = StM (Eff r) (Either e a)Defined in extensible-effects-5.0.0.1 · Control.Eff.Exception

valueexc :: Monad m => e -> m (Either e a)

Throw an error

valuewithException :: Monad m => a -> m (Either e a)

Embed a pure value

typetype Fail = Exc ()

valuethrowError :: Member (Exc e) r => e -> Eff r a

Throw an exception in an effectful computation. The type is inferred.

valuethrowError_ :: Member (Exc e) r => e -> Eff r ()

Throw an exception in an effectful computation. The type is unit, which suppresses the ghc-mod warning "A do-notation statement discarded a result of type"

valuedie :: Member Fail r => Eff r a

Makes an effect fail, preventing future effects from happening.

valuerunError :: Eff (Exc e ': r) a -> Eff r (Either e a)

Run a computation that might produce an exception.

valuerunFail :: Eff (Fail ': r) a -> Eff r (Maybe a)

Runs a failable effect, such that failed computation return Nothing, and Just the return value on success.

valuecatchError :: Member (Exc e) r => Eff r a -> (e -> Eff r a) -> Eff r a

Run a computation that might produce exceptions, and give it a way to deal with the exceptions that come up. The handler is allowed to rethrow the exception

valueonFail

:: Eff (Fail ': r) a
The fallible computation.
-> Eff r a
The computation to run on failure.
-> Eff r a

Add a default value (i.e. failure handler) to a fallible computation. This hides the fact that a failure happened.

valuerethrowError

:: Member (Exc e') r
=> e -> e'
-> Eff (Exc e ': r) a
-> Eff r a

Run a computation until it produces an exception, and convert and throw that exception in a new context.

valueliftEither :: Member (Exc e) r => Either e a -> Eff r a

Treat Lefts as exceptions and Rights as return values.

valueliftEitherM :: (Member (Exc e) r, Lifted m r) => m (Either e a) -> Eff r a

liftEither in a lifted Monad

valueliftMaybe :: Member Fail r => Maybe a -> Eff r a

Lift a maybe into the Fail effect, causing failure if it's Nothing.

valueliftMaybeM :: (Member Fail r, Lifted m r) => m (Maybe a) -> Eff r a

liftMaybe in a lifted Monad

valueignoreFail :: Eff (Fail ': r) a -> Eff r ()

Ignores a failure event. Since the event can fail, you cannot inspect its return type, because it has none on failure. To inspect it, use runFail.