| Safe Haskell | Safe |
|---|---|
| Language | Haskell2010 |
Universum.Monad.Maybe
Description
Utility functions to work with Maybe data type as monad.
- (?:) :: Maybe a -> a -> a
- whenJust :: Applicative f => Maybe a -> (a -> f ()) -> f ()
- whenJustM :: Monad m => m (Maybe a) -> (a -> m ()) -> m ()
- whenNothing :: Applicative f => Maybe a -> f a -> f a
- whenNothing_ :: Applicative f => Maybe a -> f () -> f ()
- whenNothingM :: Monad m => m (Maybe a) -> m a -> m a
- whenNothingM_ :: Monad m => m (Maybe a) -> m () -> m ()
Documentation
(?:) :: Maybe a -> a -> a infixr 0 Source #
Similar to fromMaybe but with flipped arguments.
>>>readMaybe "True" ?: FalseTrue
>>>readMaybe "Tru" ?: FalseFalse
whenJust :: Applicative f => Maybe a -> (a -> f ()) -> f () Source #
Specialized version of for_ for Maybe. It's used for code readability.
Also helps to avoid space leaks:
Foldable.mapM_ space leak.
>>>whenJust Nothing $ \b -> print (not b)>>>whenJust (Just True) $ \b -> print (not b)False
whenNothing :: Applicative f => Maybe a -> f a -> f a Source #
Performs default Applicative action if Nothing is given.
Otherwise returns content of Just pured to Applicative.
>>>whenNothing Nothing [True, False][True,False]>>>whenNothing (Just True) [True, False][True]
whenNothing_ :: Applicative f => Maybe a -> f () -> f () Source #
Performs default Applicative action if Nothing is given.
Do nothing for Just. Convenient for discarding Just content.
>>>whenNothing_ Nothing $ putTextLn "Nothing!"Nothing!>>>whenNothing_ (Just True) $ putTextLn "Nothing!"
whenNothingM :: Monad m => m (Maybe a) -> m a -> m a Source #
Monadic version of whenNothing.
whenNothingM_ :: Monad m => m (Maybe a) -> m () -> m () Source #
Monadic version of whenNothingM_.