planet-mitchell-0.0.0: Planet Mitchell

Safe HaskellSafe
LanguageHaskell2010

Except

Contents

Synopsis

ExceptT

newtype 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.

Constructors

ExceptT (m (Either e a)) 
Instances
MonadReader r m => MonadReader r (ExceptT e m)

Since: mtl-2.2

Instance details

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 #

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

Since: mtl-2.2

Instance details

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 #

(Functor f, MonadFree f m) => MonadFree f (ExceptT e m) 
Instance details

Defined in Control.Monad.Free.Class

Methods

wrap :: f (ExceptT e m a) -> ExceptT e m a #

Monad m => MonadError e (ExceptT e m)

Since: mtl-2.2

Instance details

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 #

MonadWriter w m => MonadWriter w (ExceptT e m)

Since: mtl-2.2

Instance details

Defined in Control.Monad.Writer.Class

Methods

writer :: (a, w) -> ExceptT e m a #

tell :: w -> ExceptT e m () #

listen :: ExceptT e m a -> ExceptT e m (a, w) #

pass :: ExceptT e m (a, w -> w) -> ExceptT e m a #

MonadBase b m => MonadBase b (ExceptT e m) 
Instance details

Defined in Control.Monad.Base

Methods

liftBase :: b α -> ExceptT e m α #

MonadTrans (ExceptT e) 
Instance details

Defined in Control.Monad.Trans.Except

Methods

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

MMonad (ExceptT e) 
Instance details

Defined in Control.Monad.Morph

Methods

embed :: Monad n => (forall a. m a -> ExceptT e n a) -> ExceptT e m b -> ExceptT e n b #

MFunctor (ExceptT e :: (* -> *) -> * -> *) 
Instance details

Defined in Control.Monad.Morph

Methods

hoist :: Monad m => (forall a. m a -> n a) -> ExceptT e m b -> ExceptT e n b #

Monad m => Monad (ExceptT e m) 
Instance details

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) 
Instance details

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) 
Instance details

Defined in Control.Monad.Trans.Except

Methods

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

MonadFail m => MonadFail (ExceptT e m) 
Instance details

Defined in Control.Monad.Trans.Except

Methods

fail :: String -> ExceptT e m a #

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

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) 
Instance details

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) 
Instance details

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) #

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

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] #

Contravariant m => Contravariant (ExceptT e m) 
Instance details

Defined in Data.Functor.Contravariant

Methods

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

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

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

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 #

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

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) 
Instance details

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) 
Instance details

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) 
Instance details

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) 
Instance details

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) 
Instance details

Defined in Control.Monad.Trans.Except

Methods

liftIO :: IO a -> ExceptT e m a #

MonadMask m => MonadMask (ExceptT e m)

Since: exceptions-0.9.0

Instance details

Defined in Control.Monad.Catch

Methods

mask :: ((forall a. ExceptT e m a -> ExceptT e m a) -> ExceptT e m b) -> ExceptT e m b #

uninterruptibleMask :: ((forall a. ExceptT e m a -> ExceptT e m a) -> ExceptT e m b) -> ExceptT e m b #

generalBracket :: ExceptT e m a -> (a -> ExitCase b -> ExceptT e m c) -> (a -> ExceptT e m b) -> ExceptT e m (b, c) #

MonadCatch m => MonadCatch (ExceptT e m)

Catches exceptions from the base monad.

Instance details

Defined in Control.Monad.Catch

Methods

catch :: Exception e0 => ExceptT e m a -> (e0 -> ExceptT e m a) -> ExceptT e m a #

MonadThrow m => MonadThrow (ExceptT e m)

Throws exceptions into the base monad.

Instance details

Defined in Control.Monad.Catch

Methods

throwM :: Exception e0 => e0 -> ExceptT e m a #

Divisible m => Divisible (ExceptT e m) 
Instance details

Defined in Data.Functor.Contravariant.Divisible

Methods

divide :: (a -> (b, c)) -> ExceptT e m b -> ExceptT e m c -> ExceptT e m a #

conquer :: ExceptT e m a #

PrimMonad m => PrimMonad (ExceptT e m) 
Instance details

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 #

MonadTest m => MonadTest (ExceptT x m) 
Instance details

Defined in Hedgehog.Internal.Property

Methods

liftTest :: Test a -> ExceptT x m a #

MonadGen m => MonadGen (ExceptT x m) 
Instance details

Defined in Hedgehog.Internal.Gen

Methods

liftGen :: Gen a -> ExceptT x m a #

shrinkGen :: (a -> [a]) -> ExceptT x m a -> ExceptT x m a #

pruneGen :: ExceptT x m a -> ExceptT x m a #

scaleGen :: (Size -> Size) -> ExceptT x m a -> ExceptT x m a #

freezeGen :: ExceptT x m a -> ExceptT x m (a, ExceptT x m a) #

(Functor m, Monad m) => Apply (ExceptT e m) 
Instance details

Defined in Data.Functor.Bind.Class

Methods

(<.>) :: ExceptT e m (a -> b) -> ExceptT e m a -> ExceptT e m b #

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

(<.) :: ExceptT e m a -> ExceptT e m b -> ExceptT e m a #

liftF2 :: (a -> b -> c) -> ExceptT e m a -> ExceptT e m b -> ExceptT e m c #

MonadManaged m => MonadManaged (ExceptT e m) 
Instance details

Defined in Control.Monad.Managed

Methods

using :: Managed a -> ExceptT e m a #

MonadCont m => MonadCont (ExceptT e m)

Since: mtl-2.2

Instance details

Defined in Control.Monad.Cont.Class

Methods

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

Pointed m => Pointed (ExceptT e m) 
Instance details

Defined in Data.Pointed

Methods

point :: a -> ExceptT e m a #

(Bind f, Monad f, Semigroup e, Monoid e) => Plus (ExceptT e f) 
Instance details

Defined in Data.Functor.Plus

Methods

zero :: ExceptT e f a #

(Bind f, Monad f, Semigroup e) => Alt (ExceptT e f) 
Instance details

Defined in Data.Functor.Alt

Methods

(<!>) :: ExceptT e f a -> ExceptT e f a -> ExceptT e f a #

some :: Applicative (ExceptT e f) => ExceptT e f a -> ExceptT e f [a] #

many :: Applicative (ExceptT e f) => ExceptT e f a -> ExceptT e f [a] #

(Functor m, Monad m) => Bind (ExceptT e m) 
Instance details

Defined in Data.Functor.Bind.Class

Methods

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

join :: ExceptT e m (ExceptT e m a) -> ExceptT e m a #

Zoom m n s t => Zoom (ExceptT e m) (ExceptT e n) s t 
Instance details

Defined in Control.Lens.Zoom

Methods

zoom :: LensLike' (Zoomed (ExceptT e m) c) t s -> ExceptT e m c -> ExceptT e n c #

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

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) 
Instance details

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) 
Instance details

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) 
Instance details

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 #

Wrapped (ExceptT e m a) 
Instance details

Defined in Control.Lens.Wrapped

Associated Types

type Unwrapped (ExceptT e m a) :: * #

Methods

_Wrapped' :: Iso' (ExceptT e m a) (Unwrapped (ExceptT e m a)) #

t ~ ExceptT e' m' a' => Rewrapped (ExceptT e m a) t 
Instance details

Defined in Control.Lens.Wrapped

type Zoomed (ExceptT e m) 
Instance details

Defined in Control.Lens.Zoom

type Zoomed (ExceptT e m) = FocusingErr e (Zoomed m)
type PrimState (ExceptT e m) 
Instance details

Defined in Control.Monad.Primitive

type PrimState (ExceptT e m) = PrimState m
type Unwrapped (ExceptT e m a) 
Instance details

Defined in Control.Lens.Wrapped

type Unwrapped (ExceptT e m a) = m (Either e a)

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

The inverse of ExceptT.

mapExceptT :: (m (Either e a) -> n (Either e' b)) -> ExceptT e m a -> ExceptT e' n b #

Map the unwrapped computation using the given function.

withExceptT :: Functor m => (e -> e') -> ExceptT e m a -> ExceptT e' m a #

Transform any exceptions thrown by the computation using the given function.

MonadError

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

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

Methods

throwError :: e -> m a #

Is used within a monadic computation to begin exception processing.

catchError :: 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.

Instances
MonadError () Maybe

Since: mtl-2.2.2

Instance details

Defined in Control.Monad.Error.Class

Methods

throwError :: () -> Maybe a #

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

MonadError IOException IO 
Instance details

Defined in Control.Monad.Error.Class

Methods

throwError :: IOException -> IO a #

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

MonadError e m => MonadError e (TestT m) 
Instance details

Defined in Hedgehog.Internal.Property

Methods

throwError :: e -> TestT m a #

catchError :: TestT m a -> (e -> TestT m a) -> TestT m a #

MonadError e m => MonadError e (PropertyT m) 
Instance details

Defined in Hedgehog.Internal.Property

Methods

throwError :: e -> PropertyT m a #

catchError :: PropertyT m a -> (e -> PropertyT m a) -> PropertyT m a #

MonadError e m => MonadError e (GenT m) 
Instance details

Defined in Hedgehog.Internal.Gen

Methods

throwError :: e -> GenT m a #

catchError :: GenT m a -> (e -> GenT m a) -> GenT m a #

MonadError e m => MonadError e (LogicT m) 
Instance details

Defined in Control.Monad.Logic

Methods

throwError :: e -> LogicT m a #

catchError :: LogicT m a -> (e -> LogicT m a) -> LogicT m a #

MonadError e m => MonadError e (ListT m) 
Instance details

Defined in List.Transformer

Methods

throwError :: e -> ListT m a #

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

(Functor m, MonadError e m) => MonadError e (Free m) 
Instance details

Defined in Control.Monad.Free

Methods

throwError :: e -> Free m a #

catchError :: Free m a -> (e -> Free m a) -> Free m a #

MonadError e m => MonadError e (MaybeT m) 
Instance details

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) 
Instance details

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) 
Instance details

Defined in Control.Monad.Error.Class

Methods

throwError :: e -> Either e a #

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

(Functor f, MonadError e m) => MonadError e (FreeT f m) 
Instance details

Defined in Control.Monad.Trans.Free

Methods

throwError :: e -> FreeT f m a #

catchError :: FreeT f m a -> (e -> FreeT f m a) -> FreeT f m a #

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

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) 
Instance details

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) 
Instance details

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) 
Instance details

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) 
Instance details

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

Instance details

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) 
Instance details

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 #

(Stream s, MonadError e' m) => MonadError e' (ParsecT e s m) 
Instance details

Defined in Text.Megaparsec.Internal

Methods

throwError :: e' -> ParsecT e s m a #

catchError :: ParsecT e s m a -> (e' -> ParsecT e s m a) -> ParsecT e s m a #

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

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) 
Instance details

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) 
Instance details

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 #

liftEither :: MonadError e m => Either e a -> m a #

Lifts an Either e into any MonadError e.

do { val <- liftEither =<< action1; action2 }

where action1 returns an Either to represent errors.

Since: mtl-2.2.2