Network.Gitit.Compat.Except

Documentation

data ExceptT e (m :: * -> *) a

A monad transformer that adds exceptions to other monads.

ExceptT constructs a monad parameterized over two things:

• e - The exception type.
• m - The inner monad.

The return function yields a computation that produces the given value, while >>= sequences two subcomputations, exiting on the first exception.

Instances

MonadReader r m => MonadReader r (ExceptT e m)

Since: mtl-2.2

Defined in Control.Monad.Reader.Class

Methods

ask :: ExceptT e m r

local :: (r -> r) -> ExceptT e m a -> ExceptT e m a

reader :: (r -> a) -> ExceptT e m a

FilterMonad a m => FilterMonad a (ExceptT e m)

Defined in Happstack.Server.Internal.Monads

Methods

setFilter :: (a -> a) -> ExceptT e m ()

composeFilter :: (a -> a) -> ExceptT e m ()

getFilter :: ExceptT e m b -> ExceptT e m (b, a -> a)

WebMonad a m => WebMonad a (ExceptT e m)

Defined in Happstack.Server.Internal.Monads

Methods

finishWith :: a -> ExceptT e m b

MonadBaseControl b m => MonadBaseControl b (ExceptT e m)

Defined in Control.Monad.Trans.Control

Associated Types

type StM (ExceptT e m) a :: *

Methods

liftBaseWith :: (RunInBase (ExceptT e m) b -> b a) -> ExceptT e m a

restoreM :: StM (ExceptT e m) a -> ExceptT e m a

MonadState s m => MonadState s (ExceptT e m)

Since: mtl-2.2

Defined in Control.Monad.State.Class

Methods

get :: ExceptT e m s

put :: s -> ExceptT e m ()

state :: (s -> (a, s)) -> ExceptT e m a

Monad m => MonadError e (ExceptT e m)

Since: mtl-2.2

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> ExceptT e m a

catchError :: ExceptT e m a -> (e -> ExceptT e m a) -> ExceptT e m a

MonadTrans (ExceptT e)

Defined in Control.Monad.Trans.Except

Methods

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

MonadTransControl (ExceptT e)

Defined in Control.Monad.Trans.Control

Associated Types

type StT (ExceptT e) a :: *

Methods

liftWith :: Monad m => (Run (ExceptT e) -> m a) -> ExceptT e m a

restoreT :: Monad m => m (StT (ExceptT e) a) -> ExceptT e m a

Monad m => Monad (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

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

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

return :: a -> ExceptT e m a

fail :: String -> ExceptT e m a

Functor m => Functor (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

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

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

MonadFix m => MonadFix (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

mfix :: (a -> ExceptT e m a) -> ExceptT e m a

MonadFail m => MonadFail (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

fail :: String -> ExceptT e m a

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

Defined in Control.Monad.Trans.Except

Methods

pure :: a -> ExceptT e m a

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

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

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

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

Foldable f => Foldable (ExceptT e f)

Defined in Control.Monad.Trans.Except

Methods

fold :: Monoid m => ExceptT e f m -> m

foldMap :: Monoid m => (a -> m) -> ExceptT e f a -> m

foldr :: (a -> b -> b) -> b -> ExceptT e f a -> b

foldr' :: (a -> b -> b) -> b -> ExceptT e f a -> b

foldl :: (b -> a -> b) -> b -> ExceptT e f a -> b

foldl' :: (b -> a -> b) -> b -> ExceptT e f a -> b

foldr1 :: (a -> a -> a) -> ExceptT e f a -> a

foldl1 :: (a -> a -> a) -> ExceptT e f a -> a

toList :: ExceptT e f a -> [a]

null :: ExceptT e f a -> Bool

length :: ExceptT e f a -> Int

elem :: Eq a => a -> ExceptT e f a -> Bool

maximum :: Ord a => ExceptT e f a -> a

minimum :: Ord a => ExceptT e f a -> a

sum :: Num a => ExceptT e f a -> a

product :: Num a => ExceptT e f a -> a

Traversable f => Traversable (ExceptT e f)

Defined in Control.Monad.Trans.Except

Methods

traverse :: Applicative f0 => (a -> f0 b) -> ExceptT e f a -> f0 (ExceptT e f b)

sequenceA :: Applicative f0 => ExceptT e f (f0 a) -> f0 (ExceptT e f a)

mapM :: Monad m => (a -> m b) -> ExceptT e f a -> m (ExceptT e f b)

sequence :: Monad m => ExceptT e f (m a) -> m (ExceptT e f a)

(Monad m, Monoid e) => MonadPlus (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

mzero :: ExceptT e m a

mplus :: ExceptT e m a -> ExceptT e m a -> ExceptT e m a

(Functor m, Monad m, Monoid e) => Alternative (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

empty :: ExceptT e m a

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

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

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

(Eq e, Eq1 m) => Eq1 (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

liftEq :: (a -> b -> Bool) -> ExceptT e m a -> ExceptT e m b -> Bool

(Ord e, Ord1 m) => Ord1 (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

liftCompare :: (a -> b -> Ordering) -> ExceptT e m a -> ExceptT e m b -> Ordering

(Read e, Read1 m) => Read1 (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (ExceptT e m a)

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [ExceptT e m a]

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (ExceptT e m a)

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [ExceptT e m a]

(Show e, Show1 m) => Show1 (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> ExceptT e m a -> ShowS

liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [ExceptT e m a] -> ShowS

MonadZip m => MonadZip (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

mzip :: ExceptT e m a -> ExceptT e m b -> ExceptT e m (a, b)

mzipWith :: (a -> b -> c) -> ExceptT e m a -> ExceptT e m b -> ExceptT e m c

munzip :: ExceptT e m (a, b) -> (ExceptT e m a, ExceptT e m b)

MonadIO m => MonadIO (ExceptT e m)

Defined in Control.Monad.Trans.Except

Methods

liftIO :: IO a -> ExceptT e m a

MonadResource m => MonadResource (ExceptT e m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

liftResourceT :: ResourceT IO a -> ExceptT e m a

PrimMonad m => PrimMonad (ExceptT e m)

Defined in Control.Monad.Primitive

Associated Types

type PrimState (ExceptT e m) :: *

Methods

primitive :: (State# (PrimState (ExceptT e m)) -> (#State# (PrimState (ExceptT e m)), a#)) -> ExceptT e m a

(Monad m, HasDynFlags m) => HasDynFlags (ExceptT e m)

Defined in DynFlags

Methods

getDynFlags :: ExceptT e m DynFlags

(Happstack m, Monoid e) => Happstack (ExceptT e m)

Defined in Happstack.Server.Monads

(Monad m, HasRqData m) => HasRqData (ExceptT e m)

Defined in Happstack.Server.RqData

Methods

askRqEnv :: ExceptT e m RqEnv

localRqEnv :: (RqEnv -> RqEnv) -> ExceptT e m a -> ExceptT e m a

rqDataError :: Errors String -> ExceptT e m a

ServerMonad m => ServerMonad (ExceptT e m)

Defined in Happstack.Server.Internal.Monads

Methods

askRq :: ExceptT e m Request

localRq :: (Request -> Request) -> ExceptT e m a -> ExceptT e m a

(Eq e, Eq1 m, Eq a) => Eq (ExceptT e m a)

Defined in Control.Monad.Trans.Except

Methods

(==) :: ExceptT e m a -> ExceptT e m a -> Bool

(/=) :: ExceptT e m a -> ExceptT e m a -> Bool

(Ord e, Ord1 m, Ord a) => Ord (ExceptT e m a)

Defined in Control.Monad.Trans.Except

Methods

compare :: ExceptT e m a -> ExceptT e m a -> Ordering

(<) :: ExceptT e m a -> ExceptT e m a -> Bool

(<=) :: ExceptT e m a -> ExceptT e m a -> Bool

(>) :: ExceptT e m a -> ExceptT e m a -> Bool

(>=) :: ExceptT e m a -> ExceptT e m a -> Bool

max :: ExceptT e m a -> ExceptT e m a -> ExceptT e m a

min :: ExceptT e m a -> ExceptT e m a -> ExceptT e m a

(Read e, Read1 m, Read a) => Read (ExceptT e m a)

Defined in Control.Monad.Trans.Except

Methods

readsPrec :: Int -> ReadS (ExceptT e m a)

readList :: ReadS [ExceptT e m a]

readPrec :: ReadPrec (ExceptT e m a)

readListPrec :: ReadPrec [ExceptT e m a]

(Show e, Show1 m, Show a) => Show (ExceptT e m a)

Defined in Control.Monad.Trans.Except

Methods

showsPrec :: Int -> ExceptT e m a -> ShowS

show :: ExceptT e m a -> String

showList :: [ExceptT e m a] -> ShowS

type StT (ExceptT e) a

Defined in Control.Monad.Trans.Control

type StT (ExceptT e) a = Either e a

type PrimState (ExceptT e m)

Defined in Control.Monad.Primitive

type PrimState (ExceptT e m) = PrimState m

type StM (ExceptT e m) a

Defined in Control.Monad.Trans.Control

type StM (ExceptT e m) a = ComposeSt (ExceptT e) m a

type Except e = ExceptT e Identity

The parameterizable exception monad.

Computations are either exceptions or normal values.

The return function returns a normal value, while >>= exits on the first exception. For a variant that continues after an error and collects all the errors, see Errors.

class Error a where

Methods

noMsg :: a

strMsg :: String -> a

runExceptT :: ExceptT e m a -> m (Either e a)

The inverse of ExceptT.

runExcept :: Except e a -> Either e a

Extractor for computations in the exception monad. (The inverse of except).

class Monad m => MonadError e (m :: * -> *) | m -> e

The strategy of combining computations that can throw exceptions by bypassing bound functions from the point an exception is thrown to the point that it is handled.

Is parameterized over the type of error information and the monad type constructor. It is common to use Either String as the monad type constructor for an error monad in which error descriptions take the form of strings. In that case and many other common cases the resulting monad is already defined as an instance of the MonadError class. You can also define your own error type and/or use a monad type constructor other than Either String or Either IOError. In these cases you will have to explicitly define instances of the MonadError class. (If you are using the deprecated Control.Monad.Error or Control.Monad.Trans.Error, you may also have to define an Error instance.)

Minimal complete definition

throwError, catchError

Instances

MonadError () Maybe

Since: mtl-2.2.2

Defined in Control.Monad.Error.Class

Methods

throwError :: () -> Maybe a

catchError :: Maybe a -> (() -> Maybe a) -> Maybe a

MonadError String TokenizerM

Defined in Skylighting.Tokenizer

Methods

throwError :: String -> TokenizerM a

catchError :: TokenizerM a -> (String -> TokenizerM a) -> TokenizerM a

MonadError IOException IO

Defined in Control.Monad.Error.Class

Methods

throwError :: IOException -> IO a

catchError :: IO a -> (IOException -> IO a) -> IO a

MonadError PandocError PandocIO

Defined in Text.Pandoc.Class

Methods

throwError :: PandocError -> PandocIO a

catchError :: PandocIO a -> (PandocError -> PandocIO a) -> PandocIO a

MonadError PandocError PandocPure

Defined in Text.Pandoc.Class

Methods

throwError :: PandocError -> PandocPure a

catchError :: PandocPure a -> (PandocError -> PandocPure a) -> PandocPure a

MonadError e m => MonadError e (ResourceT m)

Defined in Control.Monad.Trans.Resource.Internal

Methods

throwError :: e -> ResourceT m a

catchError :: ResourceT m a -> (e -> ResourceT m a) -> ResourceT m a

MonadError e m => MonadError e (WebT m)

Defined in Happstack.Server.Internal.Monads

Methods

throwError :: e -> WebT m a

catchError :: WebT m a -> (e -> WebT m a) -> WebT m a

(Monad m, MonadError e m) => MonadError e (ServerPartT m)

Defined in Happstack.Server.Internal.Monads

Methods

throwError :: e -> ServerPartT m a

catchError :: ServerPartT m a -> (e -> ServerPartT m a) -> ServerPartT m a

MonadError e m => MonadError e (MaybeT m)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> MaybeT m a

catchError :: MaybeT m a -> (e -> MaybeT m a) -> MaybeT m a

MonadError e m => MonadError e (ListT m)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> ListT m a

catchError :: ListT m a -> (e -> ListT m a) -> ListT m a

MonadError e (Either e)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> Either e a

catchError :: Either e a -> (e -> Either e a) -> Either e a

(Monoid w, MonadError e m) => MonadError e (WriterT w m)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> WriterT w m a

catchError :: WriterT w m a -> (e -> WriterT w m a) -> WriterT w m a

(Monoid w, MonadError e m) => MonadError e (WriterT w m)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> WriterT w m a

catchError :: WriterT w m a -> (e -> WriterT w m a) -> WriterT w m a

MonadError e m => MonadError e (StateT s m)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> StateT s m a

catchError :: StateT s m a -> (e -> StateT s m a) -> StateT s m a

MonadError e m => MonadError e (StateT s m)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> StateT s m a

catchError :: StateT s m a -> (e -> StateT s m a) -> StateT s m a

MonadError e m => MonadError e (IdentityT m)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> IdentityT m a

catchError :: IdentityT m a -> (e -> IdentityT m a) -> IdentityT m a

Monad m => MonadError e (ExceptT e m)

Since: mtl-2.2

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> ExceptT e m a

catchError :: ExceptT e m a -> (e -> ExceptT e m a) -> ExceptT e m a

(Monad m, Error e) => MonadError e (ErrorT e m)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> ErrorT e m a

catchError :: ErrorT e m a -> (e -> ErrorT e m a) -> ErrorT e m a

MonadError e m => MonadError e (ParsecT s u m)

Defined in Text.Parsec.Prim

Methods

throwError :: e -> ParsecT s u m a

catchError :: ParsecT s u m a -> (e -> ParsecT s u m a) -> ParsecT s u m a

MonadError e m => MonadError e (ConduitT i o m)

Defined in Data.Conduit.Internal.Conduit

Methods

throwError :: e -> ConduitT i o m a

catchError :: ConduitT i o m a -> (e -> ConduitT i o m a) -> ConduitT i o m a

MonadError e m => MonadError e (ReaderT r m)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> ReaderT r m a

catchError :: ReaderT r m a -> (e -> ReaderT r m a) -> ReaderT r m a

(Monoid w, MonadError e m) => MonadError e (RWST r w s m)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> RWST r w s m a

catchError :: RWST r w s m a -> (e -> RWST r w s m a) -> RWST r w s m a

(Monoid w, MonadError e m) => MonadError e (RWST r w s m)

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> RWST r w s m a

catchError :: RWST r w s m a -> (e -> RWST r w s m a) -> RWST r w s m a

MonadError e m => MonadError e (Pipe l i o u m)

Defined in Data.Conduit.Internal.Pipe

Methods

throwError :: e -> Pipe l i o u m a

catchError :: Pipe l i o u m a -> (e -> Pipe l i o u m a) -> Pipe l i o u m a

throwError :: MonadError e m => e -> m a

Is used within a monadic computation to begin exception processing.

catchError :: MonadError e m => m a -> (e -> m a) -> m a

A handler function to handle previous errors and return to normal execution. A common idiom is:

do { action1; action2; action3 } `catchError` handler

where the action functions can call throwError. Note that handler and the do-block must have the same return type.