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1. mapMaybe :: (a -> Maybe b) -> IntMap a -> IntMap b

   containers	Data.IntMap.Strict

   Map values and collect the Just results.

   let f x = if x == "a" then Just "new a" else Nothing
   mapMaybe f (fromList [(5,"a"), (3,"b")]) == singleton 5 "new a"
   

2. mapMaybeWithKey :: (Key -> a -> Maybe b) -> IntMap a -> IntMap b

   containers	Data.IntMap.Strict

   Map keys/values and collect the Just results.

   let f k _ = if k < 5 then Just ("key : " ++ (show k)) else Nothing
   mapMaybeWithKey f (fromList [(5,"a"), (3,"b")]) == singleton 3 "key : 3"
   

3. traverseMaybeWithKey :: Applicative f => (Key -> a -> f (Maybe b)) -> IntMap a -> f (IntMap b)

   containers	Data.IntMap.Strict

   Traverse keys/values and collect the Just results.

4. mapMaybe :: (a -> Maybe b) -> IntMap a -> IntMap b

   containers	Data.IntMap.Strict.Internal

   Map values and collect the Just results.

   let f x = if x == "a" then Just "new a" else Nothing
   mapMaybe f (fromList [(5,"a"), (3,"b")]) == singleton 5 "new a"
   

5. mapMaybeWithKey :: (Key -> a -> Maybe b) -> IntMap a -> IntMap b

   containers	Data.IntMap.Strict.Internal

   Map keys/values and collect the Just results.

   let f k _ = if k < 5 then Just ("key : " ++ (show k)) else Nothing
   mapMaybeWithKey f (fromList [(5,"a"), (3,"b")]) == singleton 3 "key : 3"
   

6. traverseMaybeWithKey :: Applicative f => (Key -> a -> f (Maybe b)) -> IntMap a -> f (IntMap b)

   containers	Data.IntMap.Strict.Internal

   Traverse keys/values and collect the Just results.

7. mapMaybe :: (a -> Maybe b) -> Map k a -> Map k b

   containers	Data.Map.Internal

   Map values and collect the Just results.

   let f x = if x == "a" then Just "new a" else Nothing
   mapMaybe f (fromList [(5,"a"), (3,"b")]) == singleton 5 "new a"
   

8. mapMaybeMissing :: forall (f :: Type -> Type) k x y . Applicative f => (k -> x -> Maybe y) -> WhenMissing f k x y

   containers	Data.Map.Internal

   Map over the entries whose keys are missing from the other map, optionally removing some. This is the most powerful SimpleWhenMissing tactic, but others are usually more efficient.

   mapMaybeMissing :: (k -> x -> Maybe y) -> SimpleWhenMissing k x y
   

   mapMaybeMissing f = traverseMaybeMissing (\k x -> pure (f k x))
   

   but mapMaybeMissing uses fewer unnecessary Applicative operations.

9. mapMaybeWithKey :: (k -> a -> Maybe b) -> Map k a -> Map k b

   containers	Data.Map.Internal

   Map keys/values and collect the Just results.

   let f k _ = if k < 5 then Just ("key : " ++ (show k)) else Nothing
   mapMaybeWithKey f (fromList [(5,"a"), (3,"b")]) == singleton 3 "key : 3"
   

10. traverseMaybeMissing :: Applicative f => (k -> x -> f (Maybe y)) -> WhenMissing f k x y

    containers	Data.Map.Internal

    Traverse over the entries whose keys are missing from the other map, optionally producing values to put in the result. This is the most powerful WhenMissing tactic, but others are usually more efficient.

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