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

Monad (Result e)

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

(>>=) :: Result e a -> (a -> Result e b) -> Result e b

(>>) :: Result e a -> Result e b -> Result e b

return :: a -> Result e a

Functor (Result e)

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

fmap :: (a -> b) -> Result e a -> Result e b

(<$) :: a -> Result e b -> Result e a

Applicative (Result e)

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

pure :: a -> Result e a

(<*>) :: Result e (a -> b) -> Result e a -> Result e b

liftA2 :: (a -> b -> c) -> Result e a -> Result e b -> Result e c

(*>) :: Result e a -> Result e b -> Result e b

(<*) :: Result e a -> Result e b -> Result e a

Error e => Alternative (Result e)

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

empty :: Result e a

(<|>) :: Result e a -> Result e a -> Result e a

some :: Result e a -> Result e [a]

many :: Result e a -> Result e [a]

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

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

showsPrec :: Int -> Result e a -> ShowS

show :: Result e a -> String

showList :: [Result e a] -> ShowS

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)

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

lift :: Monad m => m a -> ResultT e m a

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

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

(>>=) :: ResultT e m a -> (a -> ResultT e m b) -> ResultT e m b

(>>) :: ResultT e m a -> ResultT e m b -> ResultT e m b

return :: a -> ResultT e m a

Functor m => Functor (ResultT e m)

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

fmap :: (a -> b) -> ResultT e m a -> ResultT e m b

(<$) :: a -> ResultT e m b -> ResultT e m a

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

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

fail :: String -> ResultT e m a

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

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

pure :: a -> ResultT e m a

(<*>) :: ResultT e m (a -> b) -> ResultT e m a -> ResultT e m b

liftA2 :: (a -> b -> c) -> ResultT e m a -> ResultT e m b -> ResultT e m c

(*>) :: ResultT e m a -> ResultT e m b -> ResultT e m b

(<*) :: ResultT e m a -> ResultT e m b -> ResultT e m a

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

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

empty :: ResultT e m a

(<|>) :: ResultT e m a -> ResultT e m a -> ResultT e m a

some :: ResultT e m a -> ResultT e m [a]

many :: ResultT e m a -> ResultT e m [a]

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

Defined in Text.XML.Light.Extractors.Internal.Result

Methods

mzero :: ResultT e m a

mplus :: ResultT e m a -> ResultT e m a -> ResultT e m a

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

class Error a where

An exception to be thrown.

Minimal complete definition: noMsg or strMsg.

Minimal complete definition

Nothing

Methods

noMsg :: a

Creates an exception without a message. The default implementation is strMsg "".

strMsg :: String -> a

Creates an exception with a message. The default implementation of strMsg s is noMsg.

Instances

Error IOException

Defined in Control.Monad.Trans.Error

Methods

noMsg :: IOException

strMsg :: String -> IOException

Error ExtractionErr

Defined in Text.XML.Light.Extractors.Internal

Methods

noMsg :: ExtractionErr

strMsg :: String -> ExtractionErr

ErrorList a => Error [a]

A string can be thrown as an error.

Defined in Control.Monad.Trans.Error

Methods

noMsg :: [a]

strMsg :: String -> [a]

lift :: (MonadTrans t, Monad m) => m a -> t m a

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