Hoogle Search

Within LTS Haskell 24.6 (ghc-9.10.2)

Note that Stackage only displays results for the latest LTS and Nightly snapshot. Learn more.

Exact lookup

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

   ghc	GHC.Data.Word64Map.Strict

   mapKeysMonotonic f s == mapKeys f s, but works only when f is strictly monotonic. That is, for any values x and y, if x < y then f x < f y. The precondition is not checked. Semi-formally, we have:

   and [x < y ==> f x < f y | x <- ls, y <- ls]
   ==> mapKeysMonotonic f s == mapKeys f s
   where ls = keys s
   

   This means that f maps distinct original keys to distinct resulting keys. This function has slightly better performance than mapKeys.

   mapKeysMonotonic (\ k -> k * 2) (fromList [(5,"a"), (3,"b")]) == fromList [(6, "b"), (10, "a")]
   

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

   ghc	GHC.Data.Word64Map.Strict

   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"
   

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

   ghc	GHC.Data.Word64Map.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"
   

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

   ghc	GHC.Data.Word64Map.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"
   

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

   ghc	GHC.Data.Word64Map.Strict

   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")]
   

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

   ghc	GHC.Data.Word64Map.Strict.Internal

   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")])
   

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

   ghc	GHC.Data.Word64Map.Strict.Internal

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

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

   ghc	GHC.Data.Word64Map.Strict.Internal

   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")])
   

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

   ghc	GHC.Data.Word64Map.Strict.Internal

   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")])
   

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

    ghc	GHC.Data.Word64Map.Strict.Internal

    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")])
    

Page 101 of many | Previous | Next