Text.XML.Monad.Error

Error types

data XmlError

XML error type.

Constructors

EmptyDocument

An (invalid) empty input document was observed.

InvalidXml

Invalid XML, general parse error.

XmlChildNotFound

An immediate child element in an XML tree was not found.

XmlChildNotFoundQ QName

An immediate child element in an XML tree was not found, with name.

XmlElementNotFound

An element in an XML tree was not found.

XmlElementNotFoundQ QName

An element in an XML tree was not found, with name.

XmlAttributeNotFound

An XML element attribute was not found.

XmlAttributeNotFoundQ QName

An XML element attribute was not found, with name.

UnexpectedElementNameQ QName QName

An XML element name was different than expected, with actual and expected names.

XmlError String

A general XML error occured.

OtherError String

A general error occured.

UnspecifiedError

An unspecified general error occured.

Instances

Show XmlError

Typeable XmlError

Exception XmlError

Error XmlError

FromXmlError XmlError

class FromXmlError a where

An error type that can be constructed from XmlError.

Methods

fromXmlError :: XmlError -> a

Construct error value.

Instances

FromXmlError XmlError

Error handling

raise :: MonadError i m => i -> m a

Raise an exception.

maybeRaise :: MonadError i m => i -> Maybe a -> m a

Raise a defined exception for Nothing, return Just values.

raises :: MonadError i m => Either i a -> m a

Raise an exception for Left, return Right values.

asksEither :: (MonadReader s m, MonadError e m) => (s -> Either e a) -> m a

Like asks for a function that can return an error, as Left.

asksMaybe :: (MonadReader s m, MonadError e m) => e -> (s -> Maybe a) -> m a

Like asks for a function that can return an error, as Nothing.

try :: MonadError e m => m a -> m (Either e a)

Catch errors, and return an Left for errors, Right otherwise.

tryMaybe :: MonadError e m => m a -> m (Maybe a)

Catch errors (like try), and return Nothing for errors.

tryBool :: MonadError e m => m a -> m Bool

Catch errors (like try), and return False for errors and True for success.