| Safe Haskell | Safe |
|---|---|
| Language | Haskell98 |
Control.Exceptional
- data Exceptional x
- runExceptional :: Monad m => Exceptional x -> m x
- fromMaybe :: String -> Maybe a -> Exceptional a
- toMaybe :: Exceptional a -> Maybe a
- fromEither :: Either String a -> Exceptional a
- toEither :: Exceptional a -> Either String a
- exceptIO :: IO a -> IO (Exceptional a)
- exceptional :: MonadCatch m => m a -> m (Exceptional a)
- failures :: Foldable t => t (Exceptional x) -> [String]
- successes :: Foldable t => t (Exceptional x) -> [x]
- foldExceptional :: Foldable t => t (Exceptional x) -> Either [String] [x]
Documentation
data Exceptional x #
This is basically specialized 'Either String', or Maybe with error
messages.
Instances
| Monad Exceptional # | This is fail = Failure |
| Functor Exceptional # | |
| Applicative Exceptional # | |
| Alternative Exceptional # | |
| Eq x => Eq (Exceptional x) # | |
| Read x => Read (Exceptional x) # | |
| Show x => Show (Exceptional x) # | |
runExceptional :: Monad m => Exceptional x -> m x #
Convert Exceptional into another Monad. If you don't have proper
exception handling in your monad, this can throw errors.
runExceptional (Failure s) = fail s runExceptional (Success s) = pure s
fromMaybe :: String -> Maybe a -> Exceptional a #
Convert a Maybe to an Exceptional
fromMaybe s Nothing = fail s fromMaybe s (Just x) = pure x
toMaybe :: Exceptional a -> Maybe a #
Convert an Exceptional into a Maybe. This function disregards
the error message.
toMaybe (Success x) = Just x toMaybe (Failure _) = Nothing
fromEither :: Either String a -> Exceptional a #
Convert an Either String to an Exceptional
fromEither (Left s) = fail s fromEither (Right x) = pure x
toEither :: Exceptional a -> Either String a #
Convert an Exceptional to an Either String
toEither (Failure s) = Left s toEither (Success x) = Right x
exceptIO :: IO a -> IO (Exceptional a) #
A wrapper around tryIOError. Encapsulates I/O exceptions in the
Exceptional monad.
exceptional :: MonadCatch m => m a -> m (Exceptional a) #
Run an exception-prone action in another monad, catch the errors in Exceptional.
failures :: Foldable t => t (Exceptional x) -> [String] #
Get all of the Failures from a bunch of Exceptionals
successes :: Foldable t => t (Exceptional x) -> [x] #
Get all of the Successes from a bunch of Exceptionals
foldExceptional :: Foldable t => t (Exceptional x) -> Either [String] [x] #
Given a number of Exceptional values: