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1. mapMaybe :: (a -> Maybe b) -> [a] -> [b]

   relude	Relude.Monad.Reexport

   The mapMaybe function is a version of map which can throw out elements. In particular, the functional argument returns something of type Maybe b. If this is Nothing, no element is added on to the result list. If it is Just b, then b is included in the result list.

   Examples

   Using mapMaybe f x is a shortcut for catMaybes $ map f x in most cases:

   >>> import GHC.Internal.Text.Read ( readMaybe )
   
   >>> let readMaybeInt = readMaybe :: String -> Maybe Int
   
   >>> mapMaybe readMaybeInt ["1", "Foo", "3"]
   [1,3]
   
   >>> catMaybes $ map readMaybeInt ["1", "Foo", "3"]
   [1,3]
   

   If we map the Just constructor, the entire list should be returned:

   >>> mapMaybe Just [1,2,3]
   [1,2,3]
   

2. mapMaybe :: Ord key => key -> Accessor (Map key elem) (Maybe elem)

   distributed-process	Control.Distributed.Process.Internal.StrictContainerAccessors

   No documentation available.

3. mapMaybe :: (v1 -> Maybe v2) -> InsOrdHashMap k v1 -> InsOrdHashMap k v2

   insert-ordered-containers	Data.HashMap.Strict.InsOrd

   No documentation available.

4. mapMaybeWithKey :: (k -> v1 -> Maybe v2) -> InsOrdHashMap k v1 -> InsOrdHashMap k v2

   insert-ordered-containers	Data.HashMap.Strict.InsOrd

   No documentation available.

5. mapMaybeMProp :: (IsList c, IsList d, Eq d, Show d, Show b, Item c ~ a, Item d ~ b, Arbitrary c, Arbitrary b, Show c, Show a, CoArbitrary a, Function a) => Proxy a -> Proxy b -> (forall s . () => (a -> ST s (Maybe b)) -> c -> ST s d) -> Property

   quickcheck-classes-base	Test.QuickCheck.Classes.Base.IsList

   No documentation available.

6. mapMaybeProp :: (IsList c, Item c ~ a, Item d ~ b, Eq d, IsList d, Arbitrary b, Show d, Show b, Arbitrary c, Show c, Show a, Eq c, CoArbitrary a, Function a) => Proxy a -> Proxy b -> ((a -> Maybe b) -> c -> d) -> Property

   quickcheck-classes-base	Test.QuickCheck.Classes.Base.IsList

   Property for the mapMaybe function, which keeps elements for which the predicate holds true.

7. mapM_ :: Monad m => (a -> m x) -> Stream (Of a) m r -> m r

   streaming	Streaming.Prelude

   Reduce a stream to its return value with a monadic action.

   >>> S.mapM_ Prelude.print $ each [1..3]
   1
   2
   3
   

   >>> rest <- S.mapM_ Prelude.print $ S.splitAt 3 $ each [1..10]
   1
   2
   3
   
   >>> S.sum rest
   49 :> ()
   

8. mapMaybe :: forall (m :: Type -> Type) a b r . Monad m => (a -> Maybe b) -> Stream (Of a) m r -> Stream (Of b) m r

   streaming	Streaming.Prelude

   The mapMaybe function is a version of map which can throw out elements. In particular, the functional argument returns something of type Maybe b. If this is Nothing, no element is added on to the result Stream. If it is Just b, then b is included in the result Stream.

9. mapMaybeM :: Monad m => (a -> m (Maybe b)) -> Stream (Of a) m r -> Stream (Of b) m r

   streaming	Streaming.Prelude

   Map monadically over a stream, producing a new stream only containing the Just values.

10. mapMaybe :: Filterable f => (a -> Maybe b) -> f a -> f b

    witherable	Witherable

    Like mapMaybe.

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