| Copyright | (C) Edward Kmett 2013-2015 (c) Google Inc. 2012 |
|---|---|
| License | BSD-style (see the file LICENSE) |
| Maintainer | Edward Kmett <ekmett@gmail.com> |
| Stability | experimental |
| Portability | non-portable |
| Safe Haskell | Trustworthy |
| Language | Haskell98 |
Control.Monad.Catch.Pure
Contents
Description
Synopsis
- newtype CatchT m a = CatchT {
- runCatchT :: m (Either SomeException a)
- type Catch = CatchT Identity
- runCatch :: Catch a -> Either SomeException a
- mapCatchT :: (m (Either SomeException a) -> n (Either SomeException b)) -> CatchT m a -> CatchT n b
- module Control.Monad.Catch
Transformer
The transformers-style monad transfomer
Add Exception handling abilities to a Monad.
This should never be used in combination with IO. Think of CatchT
as an alternative base monad for use with mocking code that solely throws
exceptions via throwM.
Note: that IO monad has these abilities already, so stacking CatchT on top
of it does not add any value and can possibly be confusing:
>>>(error "Hello!" :: IO ()) `catch` (\(e :: ErrorCall) -> liftIO $ print e)Hello!
>>>runCatchT $ (error "Hello!" :: CatchT IO ()) `catch` (\(e :: ErrorCall) -> liftIO $ print e)*** Exception: Hello!
>>>runCatchT $ (throwM (ErrorCall "Hello!") :: CatchT IO ()) `catch` (\(e :: ErrorCall) -> liftIO $ print e)Hello!
Constructors
| CatchT | |
Fields
| |
Instances
| MonadTrans CatchT # | |
| MonadRWS r w s m => MonadRWS r w s (CatchT m) # | |
Defined in Control.Monad.Catch.Pure | |
| MonadWriter w m => MonadWriter w (CatchT m) # | |
| MonadState s m => MonadState s (CatchT m) # | |
| MonadReader e m => MonadReader e (CatchT m) # | |
| Monad m => Monad (CatchT m) # | |
| Monad m => Functor (CatchT m) # | |
| MonadFix m => MonadFix (CatchT m) # | |
| Monad m => MonadFail (CatchT m) # | |
| Monad m => Applicative (CatchT m) # | |
Defined in Control.Monad.Catch.Pure | |
| Foldable m => Foldable (CatchT m) # | |
Defined in Control.Monad.Catch.Pure Methods fold :: Monoid m0 => CatchT m m0 -> m0 Source # foldMap :: Monoid m0 => (a -> m0) -> CatchT m a -> m0 Source # foldMap' :: Monoid m0 => (a -> m0) -> CatchT m a -> m0 Source # foldr :: (a -> b -> b) -> b -> CatchT m a -> b Source # foldr' :: (a -> b -> b) -> b -> CatchT m a -> b Source # foldl :: (b -> a -> b) -> b -> CatchT m a -> b Source # foldl' :: (b -> a -> b) -> b -> CatchT m a -> b Source # foldr1 :: (a -> a -> a) -> CatchT m a -> a Source # foldl1 :: (a -> a -> a) -> CatchT m a -> a Source # toList :: CatchT m a -> [a] Source # null :: CatchT m a -> Bool Source # length :: CatchT m a -> Int Source # elem :: Eq a => a -> CatchT m a -> Bool Source # maximum :: Ord a => CatchT m a -> a Source # minimum :: Ord a => CatchT m a -> a Source # | |
| (Monad m, Traversable m) => Traversable (CatchT m) # | |
Defined in Control.Monad.Catch.Pure | |
| MonadIO m => MonadIO (CatchT m) # | |
| Monad m => Alternative (CatchT m) # | |
| Monad m => MonadPlus (CatchT m) # | |
| Monad m => MonadMask (CatchT m) # | Note: This instance is only valid if the underlying monad has a single exit point! For example, |
Defined in Control.Monad.Catch.Pure Methods mask :: ((forall a. CatchT m a -> CatchT m a) -> CatchT m b) -> CatchT m b Source # uninterruptibleMask :: ((forall a. CatchT m a -> CatchT m a) -> CatchT m b) -> CatchT m b Source # generalBracket :: CatchT m a -> (a -> ExitCase b -> CatchT m c) -> (a -> CatchT m b) -> CatchT m (b, c) Source # | |
| Monad m => MonadCatch (CatchT m) # | |
| Monad m => MonadThrow (CatchT m) # | |
mapCatchT :: (m (Either SomeException a) -> n (Either SomeException b)) -> CatchT m a -> CatchT n b Source #
Typeclass
The mtl style typeclass
module Control.Monad.Catch