Polysemy.Fail

Effect

newtype Fail m a

Constructors

Fail String

Interpretations

runFail :: Sem (Fail ': r) a -> Sem r (Either String a)

Run a Fail effect purely.

failToError :: Member (Error e) r => (String -> e) -> Sem (Fail ': r) a -> Sem r a

Transform a Fail effect into an Error e effect, through providing a function for transforming any failure to an exception.

failToNonDet :: Member NonDet r => Sem (Fail ': r) a -> Sem r a

Transform a Fail effect into a NonDet effect, through mapping any failure to empty.

failToEmbed :: forall m r a. (Member (Embed m) r, MonadFail m) => Sem (Fail ': r) a -> Sem r a

Run a Fail effect in terms of an underlying MonadFail instance.