Text.XML.Light.Extractors.Internal.Result

Documentation

data Result e a

Result is like Either but with two error states, Fail and Fatal.

Fail is precisely analogous to Left while Fatal has short cut semantics for Alternative.

The idea is that Fatal errors cannot be circumvented by <|> etc.

Constructors

Fatal e

Fail e

Ok a

Instances

Error e => Alternative (Result e)

Monad (Result e)

Functor (Result e)

Applicative (Result e)

(Show e, Show a) => Show (Result e a)

toEither :: Result a b -> Either a b

Maps Fail and Fatal to Left.

escalate :: Result e a -> Result e a

Maps Fail to Fatal.

data ResultT e m a

Instances

Error e => MonadTrans (ResultT e)

(Functor m, Monad m, Error e) => Alternative (ResultT e m)

(Monad m, Error e) => Monad (ResultT e m)

Functor m => Functor (ResultT e m)

(Error e, Monad m) => MonadPlus (ResultT e m)

(Functor m, Monad m) => Applicative (ResultT e m)

runResultT :: ResultT e m a -> m (Result e a)

throwError :: (Error e, Monad m) => e -> ResultT e m a

throwFatal :: (Error e, Monad m) => e -> ResultT e m a

mapResult :: (Functor m, Monad m) => (Result e1 a1 -> Result e a) -> ResultT e1 m a1 -> ResultT e m a

module Control.Monad.Trans.Error

lift :: MonadTrans t => forall m a. Monad m => m a -> t m a

Lift a computation from the argument monad to the constructed monad.