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

   Cabal-syntax	Distribution.Compat.Prelude

   No documentation available.

2. mapMaybeT :: (a -> Maybe b) -> [[a]] -> [[b]]

   leancheck	Test.LeanCheck.Tiers

   Like mapMaybe but for tiers.

3. 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.

4. 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.

5. mapMaybeWithKey :: GCompare k2 => (forall (v :: k1) . () => k2 v -> f v -> Maybe (g v)) -> DMap k2 f -> DMap k2 g

   dependent-map	Data.Dependent.Map

   O(n). Map keys/values and collect the Just results.

6. mapM_ :: (Foldable t, Monad m) => (a -> m b) -> t a -> m ()

   relude	Relude.Foldable.Reexport

   Map each element of a structure to a monadic action, evaluate these actions from left to right, and ignore the results. For a version that doesn't ignore the results see mapM. mapM_ is just like traverse_, but specialised to monadic actions.

7. mapMaybeM :: Monad m => (a -> m (Maybe b)) -> [a] -> m [b]

   relude	Relude.Monad.Maybe

   The monadic version of the mapMaybe function.

   >>> :{
   evenInHalf :: Int -> IO (Maybe Int)
   evenInHalf n
   | even n = pure $ Just $ n `div` 2
   | otherwise = pure Nothing
   :}
   

   >>> mapMaybeM evenInHalf [1..10]
   [1,2,3,4,5]
   

8. 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]
   

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

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

   No documentation available.

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

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

    No documentation available.

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