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

   ghc	GHC.Data.Word64Map.Lazy

   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.Lazy

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

   ghc	GHC.Data.Word64Map.Lazy

   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"
   

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

   ghc	GHC.Data.Word64Map.Lazy

   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")]
   

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

   ghc	GHC.Data.Word64Map.Strict

   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")])
   

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

   ghc	GHC.Data.Word64Map.Strict

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

7. mapAccumWithKey :: (a -> Key -> b -> (a, c)) -> a -> Word64Map b -> (a, Word64Map c)

   ghc	GHC.Data.Word64Map.Strict

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

   let f a k b = (a ++ " " ++ (show k) ++ "-" ++ b, b ++ "X")
   mapAccumWithKey f "Everything:" (fromList [(5,"a"), (3,"b")]) == ("Everything: 3-b 5-a", fromList [(3, "bX"), (5, "aX")])
   

8. mapEither :: (a -> Either b c) -> Word64Map a -> (Word64Map b, Word64Map c)

   ghc	GHC.Data.Word64Map.Strict

   Map values and separate the Left and Right results.

   let f a = if a < "c" then Left a else Right a
   mapEither f (fromList [(5,"a"), (3,"b"), (1,"x"), (7,"z")])
   == (fromList [(3,"b"), (5,"a")], fromList [(1,"x"), (7,"z")])
   
   mapEither (\ a -> Right a) (fromList [(5,"a"), (3,"b"), (1,"x"), (7,"z")])
   == (empty, fromList [(5,"a"), (3,"b"), (1,"x"), (7,"z")])
   

9. mapEitherWithKey :: (Key -> a -> Either b c) -> Word64Map a -> (Word64Map b, Word64Map c)

   ghc	GHC.Data.Word64Map.Strict

   Map keys/values and separate the Left and Right results.

   let f k a = if k < 5 then Left (k * 2) else Right (a ++ a)
   mapEitherWithKey f (fromList [(5,"a"), (3,"b"), (1,"x"), (7,"z")])
   == (fromList [(1,2), (3,6)], fromList [(5,"aa"), (7,"zz")])
   
   mapEitherWithKey (\_ a -> Right a) (fromList [(5,"a"), (3,"b"), (1,"x"), (7,"z")])
   == (empty, fromList [(1,"x"), (3,"b"), (5,"a"), (7,"z")])
   

10. mapKeys :: (Key -> Key) -> Word64Map a -> Word64Map a

    ghc	GHC.Data.Word64Map.Strict

    mapKeys 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 value at the greatest of the original keys is retained.

    mapKeys (+ 1) (fromList [(5,"a"), (3,"b")])                        == fromList [(4, "b"), (6, "a")]
    mapKeys (\ _ -> 1) (fromList [(1,"b"), (2,"a"), (3,"d"), (4,"c")]) == singleton 1 "c"
    mapKeys (\ _ -> 3) (fromList [(1,"b"), (2,"a"), (3,"d"), (4,"c")]) == singleton 3 "c"
    

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