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1. mapKeysWith :: (a -> a -> a) -> (Key -> Key) -> Word64Map a -> Word64Map a

   ghc	GHC.Data.Word64Map.Internal

   mapKeysWith c f s is the map obtained by applying f to each key of s. The size of the result may be smaller if f maps two or more distinct keys to the same new key. In this case the associated values will be combined using c.

   mapKeysWith (++) (\ _ -> 1) (fromList [(1,"b"), (2,"a"), (3,"d"), (4,"c")]) == singleton 1 "cdab"
   mapKeysWith (++) (\ _ -> 3) (fromList [(1,"b"), (2,"a"), (3,"d"), (4,"c")]) == singleton 3 "cdab"
   

2. mapMaybe :: (a -> Maybe b) -> Word64Map a -> Word64Map b

   ghc	GHC.Data.Word64Map.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"
   

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

   ghc	GHC.Data.Word64Map.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 :: (Key -> x -> Maybe y) -> SimpleWhenMissing x y
   

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

   but mapMaybeMissing uses fewer unnecessary Applicative operations.

4. mapMaybeWithKey :: (Key -> a -> Maybe b) -> Word64Map a -> Word64Map b

   ghc	GHC.Data.Word64Map.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"
   

5. mapMissing :: forall (f :: Type -> Type) x y . Applicative f => (Key -> x -> y) -> WhenMissing f x y

   ghc	GHC.Data.Word64Map.Internal

   Map over the entries whose keys are missing from the other map.

   mapMissing :: (k -> x -> y) -> SimpleWhenMissing x y
   

   mapMissing f = mapMaybeMissing (\k x -> Just $ f k x)
   

   but mapMissing is somewhat faster.

6. mapWhenMatched :: forall (f :: Type -> Type) a b x y . Functor f => (a -> b) -> WhenMatched f x y a -> WhenMatched f x y b

   ghc	GHC.Data.Word64Map.Internal

   Map covariantly over a WhenMatched f x y.

7. mapWhenMissing :: forall (f :: Type -> Type) a b x . (Applicative f, Monad f) => (a -> b) -> WhenMissing f x a -> WhenMissing f x b

   ghc	GHC.Data.Word64Map.Internal

   Map covariantly over a WhenMissing f x.

8. mapWithKey :: (Key -> a -> b) -> Word64Map a -> Word64Map b

   ghc	GHC.Data.Word64Map.Internal

   Map a function over all values in the map.

   let f key x = (show key) ++ ":" ++ x
   mapWithKey f (fromList [(5,"a"), (3,"b")]) == fromList [(3, "3:b"), (5, "5:a")]
   

9. mapAccum :: (a -> b -> (a, c)) -> a -> Word64Map b -> (a, Word64Map c)

   ghc	GHC.Data.Word64Map.Lazy

   The function mapAccum threads an accumulating argument through the map in ascending order of keys.

   let f a b = (a ++ b, b ++ "X")
   mapAccum f "Everything: " (fromList [(5,"a"), (3,"b")]) == ("Everything: ba", fromList [(3, "bX"), (5, "aX")])
   

10. mapAccumRWithKey :: (a -> Key -> b -> (a, c)) -> a -> Word64Map b -> (a, Word64Map c)

    ghc	GHC.Data.Word64Map.Lazy

    The function mapAccumRWithKey threads an accumulating argument through the map in descending order of keys.

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