containers-0.5.11.0: Assorted concrete container types

Data.IntMap.Strict

Description

An efficient implementation of maps from integer keys to values (dictionaries).

API of this module is strict in both the keys and the values. If you need value-lazy maps, use Data.IntMap.Lazy instead. The IntMap type itself is shared between the lazy and strict modules, meaning that the same IntMap value can be passed to functions in both modules (although that is rarely needed).

These modules are intended to be imported qualified, to avoid name clashes with Prelude functions, e.g.

 import Data.IntMap.Strict (IntMap)
import qualified Data.IntMap.Strict as IntMap

The implementation is based on big-endian patricia trees. This data structure performs especially well on binary operations like union and intersection. However, my benchmarks show that it is also (much) faster on insertions and deletions when compared to a generic size-balanced map implementation (see Data.Map).

• Chris Okasaki and Andy Gill, "Fast Mergeable Integer Maps", Workshop on ML, September 1998, pages 77-86, http://citeseer.ist.psu.edu/okasaki98fast.html
• D.R. Morrison, "/PATRICIA -- Practical Algorithm To Retrieve Information Coded In Alphanumeric/", Journal of the ACM, 15(4), October 1968, pages 514-534.

Operation comments contain the operation time complexity in the Big-O notation http://en.wikipedia.org/wiki/Big_O_notation. Many operations have a worst-case complexity of O(min(n,W)). This means that the operation can become linear in the number of elements with a maximum of W -- the number of bits in an Int (32 or 64).

Be aware that the Functor, Traversable and Data instances are the same as for the Data.IntMap.Lazy module, so if they are used on strict maps, the resulting maps will be lazy.

Synopsis

# Strictness properties

This module satisfies the following strictness properties:

1. Key arguments are evaluated to WHNF;
2. Keys and values are evaluated to WHNF before they are stored in the map.

Here's an example illustrating the first property:

delete undefined m  ==  undefined

Here are some examples that illustrate the second property:

map (\ v -> undefined) m  ==  undefined      -- m is not empty
mapKeys (\ k -> undefined) m  ==  undefined  -- m is not empty

# Map type

data IntMap a Source #

A map of integers to values a.

Instances
 # Instance detailsDefined in Data.IntMap.Internal Methodsfmap :: (a -> b) -> IntMap a -> IntMap b Source #(<$) :: a -> IntMap b -> IntMap a Source # # Instance detailsDefined in Data.IntMap.Internal Methodsfold :: Monoid m => IntMap m -> m Source #foldMap :: Monoid m => (a -> m) -> IntMap a -> m Source #foldr :: (a -> b -> b) -> b -> IntMap a -> b Source #foldr' :: (a -> b -> b) -> b -> IntMap a -> b Source #foldl :: (b -> a -> b) -> b -> IntMap a -> b Source #foldl' :: (b -> a -> b) -> b -> IntMap a -> b Source #foldr1 :: (a -> a -> a) -> IntMap a -> a Source #foldl1 :: (a -> a -> a) -> IntMap a -> a Source #toList :: IntMap a -> [a] Source #null :: IntMap a -> Bool Source #length :: IntMap a -> Int Source #elem :: Eq a => a -> IntMap a -> Bool Source #maximum :: Ord a => IntMap a -> a Source #minimum :: Ord a => IntMap a -> a Source #sum :: Num a => IntMap a -> a Source #product :: Num a => IntMap a -> a Source # # Instance detailsDefined in Data.IntMap.Internal Methodstraverse :: Applicative f => (a -> f b) -> IntMap a -> f (IntMap b) Source #sequenceA :: Applicative f => IntMap (f a) -> f (IntMap a) Source #mapM :: Monad m => (a -> m b) -> IntMap a -> m (IntMap b) Source #sequence :: Monad m => IntMap (m a) -> m (IntMap a) Source # # Since: containers-0.5.9 Instance detailsDefined in Data.IntMap.Internal MethodsliftEq :: (a -> b -> Bool) -> IntMap a -> IntMap b -> Bool Source # # Since: containers-0.5.9 Instance detailsDefined in Data.IntMap.Internal MethodsliftCompare :: (a -> b -> Ordering) -> IntMap a -> IntMap b -> Ordering Source # # Since: containers-0.5.9 Instance detailsDefined in Data.IntMap.Internal MethodsliftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (IntMap a) Source #liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [IntMap a] Source #liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (IntMap a) Source #liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [IntMap a] Source # # Since: containers-0.5.9 Instance detailsDefined in Data.IntMap.Internal MethodsliftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> IntMap a -> ShowS Source #liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [IntMap a] -> ShowS Source # IsList (IntMap a) # Since: containers-0.5.6.2 Instance detailsDefined in Data.IntMap.Internal Associated Typestype Item (IntMap a) :: * Source # MethodsfromList :: [Item (IntMap a)] -> IntMap a Source #fromListN :: Int -> [Item (IntMap a)] -> IntMap a Source #toList :: IntMap a -> [Item (IntMap a)] Source # Eq a => Eq (IntMap a) # Instance detailsDefined in Data.IntMap.Internal Methods(==) :: IntMap a -> IntMap a -> Bool Source #(/=) :: IntMap a -> IntMap a -> Bool Source # Data a => Data (IntMap a) # Instance detailsDefined in Data.IntMap.Internal Methodsgfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> IntMap a -> c (IntMap a) Source #gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (IntMap a) Source #dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (IntMap a)) Source #dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (IntMap a)) Source #gmapT :: (forall b. Data b => b -> b) -> IntMap a -> IntMap a Source #gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> IntMap a -> r Source #gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> IntMap a -> r Source #gmapQ :: (forall d. Data d => d -> u) -> IntMap a -> [u] Source #gmapQi :: Int -> (forall d. Data d => d -> u) -> IntMap a -> u Source #gmapM :: Monad m => (forall d. Data d => d -> m d) -> IntMap a -> m (IntMap a) Source #gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> IntMap a -> m (IntMap a) Source #gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> IntMap a -> m (IntMap a) Source # Ord a => Ord (IntMap a) # Instance detailsDefined in Data.IntMap.Internal Methodscompare :: IntMap a -> IntMap a -> Ordering Source #(<) :: IntMap a -> IntMap a -> Bool Source #(<=) :: IntMap a -> IntMap a -> Bool Source #(>) :: IntMap a -> IntMap a -> Bool Source #(>=) :: IntMap a -> IntMap a -> Bool Source #max :: IntMap a -> IntMap a -> IntMap a Source #min :: IntMap a -> IntMap a -> IntMap a Source # Read e => Read (IntMap e) # Instance detailsDefined in Data.IntMap.Internal Methods Show a => Show (IntMap a) # Instance detailsDefined in Data.IntMap.Internal MethodsshowsPrec :: Int -> IntMap a -> ShowS Source #show :: IntMap a -> String Source #showList :: [IntMap a] -> ShowS Source # # Since: containers-0.5.7 Instance detailsDefined in Data.IntMap.Internal Methods(<>) :: IntMap a -> IntMap a -> IntMap a Source #sconcat :: NonEmpty (IntMap a) -> IntMap a Source #stimes :: Integral b => b -> IntMap a -> IntMap a Source # Monoid (IntMap a) # Instance detailsDefined in Data.IntMap.Internal Methodsmappend :: IntMap a -> IntMap a -> IntMap a Source #mconcat :: [IntMap a] -> IntMap a Source # NFData a => NFData (IntMap a) # Instance detailsDefined in Data.IntMap.Internal Methodsrnf :: IntMap a -> () Source # type Item (IntMap a) # Instance detailsDefined in Data.IntMap.Internal type Item (IntMap a) = (Key, a) type Key = Int Source # # Operators (!) :: IntMap a -> Key -> a Source # O(min(n,W)). Find the value at a key. Calls error when the element can not be found. fromList [(5,'a'), (3,'b')] ! 1 Error: element not in the map fromList [(5,'a'), (3,'b')] ! 5 == 'a' (!?) :: IntMap a -> Key -> Maybe a infixl 9 Source # O(min(n,W)). Find the value at a key. Returns Nothing when the element can not be found. fromList [(5,'a'), (3,'b')] !? 1 == Nothing fromList [(5,'a'), (3,'b')] !? 5 == Just 'a' Since: containers-0.5.11 (\\) :: IntMap a -> IntMap b -> IntMap a infixl 9 Source # Same as difference. # Query null :: IntMap a -> Bool Source # O(1). Is the map empty? Data.IntMap.null (empty) == True Data.IntMap.null (singleton 1 'a') == False size :: IntMap a -> Int Source # O(n). Number of elements in the map. size empty == 0 size (singleton 1 'a') == 1 size (fromList([(1,'a'), (2,'c'), (3,'b')])) == 3 member :: Key -> IntMap a -> Bool Source # O(min(n,W)). Is the key a member of the map? member 5 (fromList [(5,'a'), (3,'b')]) == True member 1 (fromList [(5,'a'), (3,'b')]) == False notMember :: Key -> IntMap a -> Bool Source # O(min(n,W)). Is the key not a member of the map? notMember 5 (fromList [(5,'a'), (3,'b')]) == False notMember 1 (fromList [(5,'a'), (3,'b')]) == True lookup :: Key -> IntMap a -> Maybe a Source # O(min(n,W)). Lookup the value at a key in the map. See also lookup. findWithDefault :: a -> Key -> IntMap a -> a Source # O(min(n,W)). The expression (findWithDefault def k map) returns the value at key k or returns def when the key is not an element of the map. findWithDefault 'x' 1 (fromList [(5,'a'), (3,'b')]) == 'x' findWithDefault 'x' 5 (fromList [(5,'a'), (3,'b')]) == 'a' lookupLT :: Key -> IntMap a -> Maybe (Key, a) Source # O(log n). Find largest key smaller than the given one and return the corresponding (key, value) pair. lookupLT 3 (fromList [(3,'a'), (5,'b')]) == Nothing lookupLT 4 (fromList [(3,'a'), (5,'b')]) == Just (3, 'a') lookupGT :: Key -> IntMap a -> Maybe (Key, a) Source # O(log n). Find smallest key greater than the given one and return the corresponding (key, value) pair. lookupGT 4 (fromList [(3,'a'), (5,'b')]) == Just (5, 'b') lookupGT 5 (fromList [(3,'a'), (5,'b')]) == Nothing lookupLE :: Key -> IntMap a -> Maybe (Key, a) Source # O(log n). Find largest key smaller or equal to the given one and return the corresponding (key, value) pair. lookupLE 2 (fromList [(3,'a'), (5,'b')]) == Nothing lookupLE 4 (fromList [(3,'a'), (5,'b')]) == Just (3, 'a') lookupLE 5 (fromList [(3,'a'), (5,'b')]) == Just (5, 'b') lookupGE :: Key -> IntMap a -> Maybe (Key, a) Source # O(log n). Find smallest key greater or equal to the given one and return the corresponding (key, value) pair. lookupGE 3 (fromList [(3,'a'), (5,'b')]) == Just (3, 'a') lookupGE 4 (fromList [(3,'a'), (5,'b')]) == Just (5, 'b') lookupGE 6 (fromList [(3,'a'), (5,'b')]) == Nothing # Construction O(1). The empty map. empty == fromList [] size empty == 0 singleton :: Key -> a -> IntMap a Source # O(1). A map of one element. singleton 1 'a' == fromList [(1, 'a')] size (singleton 1 'a') == 1 ## Insertion insert :: Key -> a -> IntMap a -> IntMap a Source # O(min(n,W)). Insert a new key/value pair in the map. If the key is already present in the map, the associated value is replaced with the supplied value, i.e. insert is equivalent to insertWith const. insert 5 'x' (fromList [(5,'a'), (3,'b')]) == fromList [(3, 'b'), (5, 'x')] insert 7 'x' (fromList [(5,'a'), (3,'b')]) == fromList [(3, 'b'), (5, 'a'), (7, 'x')] insert 5 'x' empty == singleton 5 'x' insertWith :: (a -> a -> a) -> Key -> a -> IntMap a -> IntMap a Source # O(min(n,W)). Insert with a combining function. insertWith f key value mp will insert the pair (key, value) into mp if key does not exist in the map. If the key does exist, the function will insert f new_value old_value. insertWith (++) 5 "xxx" (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "xxxa")] insertWith (++) 7 "xxx" (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "a"), (7, "xxx")] insertWith (++) 5 "xxx" empty == singleton 5 "xxx" insertWithKey :: (Key -> a -> a -> a) -> Key -> a -> IntMap a -> IntMap a Source # O(min(n,W)). Insert with a combining function. insertWithKey f key value mp will insert the pair (key, value) into mp if key does not exist in the map. If the key does exist, the function will insert f key new_value old_value. let f key new_value old_value = (show key) ++ ":" ++ new_value ++ "|" ++ old_value insertWithKey f 5 "xxx" (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "5:xxx|a")] insertWithKey f 7 "xxx" (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "a"), (7, "xxx")] insertWithKey f 5 "xxx" empty == singleton 5 "xxx" If the key exists in the map, this function is lazy in x but strict in the result of f. insertLookupWithKey :: (Key -> a -> a -> a) -> Key -> a -> IntMap a -> (Maybe a, IntMap a) Source # O(min(n,W)). The expression (insertLookupWithKey f k x map) is a pair where the first element is equal to (lookup k map) and the second element equal to (insertWithKey f k x map). let f key new_value old_value = (show key) ++ ":" ++ new_value ++ "|" ++ old_value insertLookupWithKey f 5 "xxx" (fromList [(5,"a"), (3,"b")]) == (Just "a", fromList [(3, "b"), (5, "5:xxx|a")]) insertLookupWithKey f 7 "xxx" (fromList [(5,"a"), (3,"b")]) == (Nothing, fromList [(3, "b"), (5, "a"), (7, "xxx")]) insertLookupWithKey f 5 "xxx" empty == (Nothing, singleton 5 "xxx") This is how to define insertLookup using insertLookupWithKey: let insertLookup kx x t = insertLookupWithKey (\_ a _ -> a) kx x t insertLookup 5 "x" (fromList [(5,"a"), (3,"b")]) == (Just "a", fromList [(3, "b"), (5, "x")]) insertLookup 7 "x" (fromList [(5,"a"), (3,"b")]) == (Nothing, fromList [(3, "b"), (5, "a"), (7, "x")]) ## Delete/Update delete :: Key -> IntMap a -> IntMap a Source # O(min(n,W)). Delete a key and its value from the map. When the key is not a member of the map, the original map is returned. delete 5 (fromList [(5,"a"), (3,"b")]) == singleton 3 "b" delete 7 (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "a")] delete 5 empty == empty adjust :: (a -> a) -> Key -> IntMap a -> IntMap a Source # O(min(n,W)). Adjust a value at a specific key. When the key is not a member of the map, the original map is returned. adjust ("new " ++) 5 (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "new a")] adjust ("new " ++) 7 (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "a")] adjust ("new " ++) 7 empty == empty adjustWithKey :: (Key -> a -> a) -> Key -> IntMap a -> IntMap a Source # O(min(n,W)). Adjust a value at a specific key. When the key is not a member of the map, the original map is returned. let f key x = (show key) ++ ":new " ++ x adjustWithKey f 5 (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "5:new a")] adjustWithKey f 7 (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "a")] adjustWithKey f 7 empty == empty update :: (a -> Maybe a) -> Key -> IntMap a -> IntMap a Source # O(min(n,W)). The expression (update f k map) updates the value x at k (if it is in the map). If (f x) is Nothing, the element is deleted. If it is (Just y), the key k is bound to the new value y. let f x = if x == "a" then Just "new a" else Nothing update f 5 (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "new a")] update f 7 (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "a")] update f 3 (fromList [(5,"a"), (3,"b")]) == singleton 5 "a" updateWithKey :: (Key -> a -> Maybe a) -> Key -> IntMap a -> IntMap a Source # O(min(n,W)). The expression (update f k map) updates the value x at k (if it is in the map). If (f k x) is Nothing, the element is deleted. If it is (Just y), the key k is bound to the new value y. let f k x = if x == "a" then Just ((show k) ++ ":new a") else Nothing updateWithKey f 5 (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "5:new a")] updateWithKey f 7 (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "a")] updateWithKey f 3 (fromList [(5,"a"), (3,"b")]) == singleton 5 "a" updateLookupWithKey :: (Key -> a -> Maybe a) -> Key -> IntMap a -> (Maybe a, IntMap a) Source # O(min(n,W)). Lookup and update. The function returns original value, if it is updated. This is different behavior than updateLookupWithKey. Returns the original key value if the map entry is deleted. let f k x = if x == "a" then Just ((show k) ++ ":new a") else Nothing updateLookupWithKey f 5 (fromList [(5,"a"), (3,"b")]) == (Just "a", fromList [(3, "b"), (5, "5:new a")]) updateLookupWithKey f 7 (fromList [(5,"a"), (3,"b")]) == (Nothing, fromList [(3, "b"), (5, "a")]) updateLookupWithKey f 3 (fromList [(5,"a"), (3,"b")]) == (Just "b", singleton 5 "a") alter :: (Maybe a -> Maybe a) -> Key -> IntMap a -> IntMap a Source # O(min(n,W)). The expression (alter f k map) alters the value x at k, or absence thereof. alter can be used to insert, delete, or update a value in an IntMap. In short : lookup k (alter f k m) = f (lookup k m). alterF :: Functor f => (Maybe a -> f (Maybe a)) -> Key -> IntMap a -> f (IntMap a) Source # O(log n). The expression (alterF f k map) alters the value x at k, or absence thereof. alterF can be used to inspect, insert, delete, or update a value in an IntMap. In short : lookup k$ alterF f k m = f (lookup k m).

Example:

interactiveAlter :: Int -> IntMap String -> IO (IntMap String)
interactiveAlter k m = alterF f k m where
f Nothing -> do
putStrLn $show k ++ " was not found in the map. Would you like to add it?" getUserResponse1 :: IO (Maybe String) f (Just old) -> do putStrLn "The key is currently bound to " ++ show old ++ ". Would you like to change or delete it?" getUserresponse2 :: IO (Maybe String)  alterF is the most general operation for working with an individual key that may or may not be in a given map. # Combine ## Union union :: IntMap a -> IntMap a -> IntMap a Source # O(n+m). The (left-biased) union of two maps. It prefers the first map when duplicate keys are encountered, i.e. (union == unionWith const). union (fromList [(5, "a"), (3, "b")]) (fromList [(5, "A"), (7, "C")]) == fromList [(3, "b"), (5, "a"), (7, "C")] unionWith :: (a -> a -> a) -> IntMap a -> IntMap a -> IntMap a Source # O(n+m). The union with a combining function. unionWith (++) (fromList [(5, "a"), (3, "b")]) (fromList [(5, "A"), (7, "C")]) == fromList [(3, "b"), (5, "aA"), (7, "C")] unionWithKey :: (Key -> a -> a -> a) -> IntMap a -> IntMap a -> IntMap a Source # O(n+m). The union with a combining function. let f key left_value right_value = (show key) ++ ":" ++ left_value ++ "|" ++ right_value unionWithKey f (fromList [(5, "a"), (3, "b")]) (fromList [(5, "A"), (7, "C")]) == fromList [(3, "b"), (5, "5:a|A"), (7, "C")] unions :: [IntMap a] -> IntMap a Source # The union of a list of maps. unions [(fromList [(5, "a"), (3, "b")]), (fromList [(5, "A"), (7, "C")]), (fromList [(5, "A3"), (3, "B3")])] == fromList [(3, "b"), (5, "a"), (7, "C")] unions [(fromList [(5, "A3"), (3, "B3")]), (fromList [(5, "A"), (7, "C")]), (fromList [(5, "a"), (3, "b")])] == fromList [(3, "B3"), (5, "A3"), (7, "C")] unionsWith :: (a -> a -> a) -> [IntMap a] -> IntMap a Source # The union of a list of maps, with a combining operation. unionsWith (++) [(fromList [(5, "a"), (3, "b")]), (fromList [(5, "A"), (7, "C")]), (fromList [(5, "A3"), (3, "B3")])] == fromList [(3, "bB3"), (5, "aAA3"), (7, "C")] ## Difference difference :: IntMap a -> IntMap b -> IntMap a Source # O(n+m). Difference between two maps (based on keys). difference (fromList [(5, "a"), (3, "b")]) (fromList [(5, "A"), (7, "C")]) == singleton 3 "b" differenceWith :: (a -> b -> Maybe a) -> IntMap a -> IntMap b -> IntMap a Source # O(n+m). Difference with a combining function. let f al ar = if al == "b" then Just (al ++ ":" ++ ar) else Nothing differenceWith f (fromList [(5, "a"), (3, "b")]) (fromList [(5, "A"), (3, "B"), (7, "C")]) == singleton 3 "b:B" differenceWithKey :: (Key -> a -> b -> Maybe a) -> IntMap a -> IntMap b -> IntMap a Source # O(n+m). Difference with a combining function. When two equal keys are encountered, the combining function is applied to the key and both values. If it returns Nothing, the element is discarded (proper set difference). If it returns (Just y), the element is updated with a new value y. let f k al ar = if al == "b" then Just ((show k) ++ ":" ++ al ++ "|" ++ ar) else Nothing differenceWithKey f (fromList [(5, "a"), (3, "b")]) (fromList [(5, "A"), (3, "B"), (10, "C")]) == singleton 3 "3:b|B" ## Intersection intersection :: IntMap a -> IntMap b -> IntMap a Source # O(n+m). The (left-biased) intersection of two maps (based on keys). intersection (fromList [(5, "a"), (3, "b")]) (fromList [(5, "A"), (7, "C")]) == singleton 5 "a" intersectionWith :: (a -> b -> c) -> IntMap a -> IntMap b -> IntMap c Source # O(n+m). The intersection with a combining function. intersectionWith (++) (fromList [(5, "a"), (3, "b")]) (fromList [(5, "A"), (7, "C")]) == singleton 5 "aA" intersectionWithKey :: (Key -> a -> b -> c) -> IntMap a -> IntMap b -> IntMap c Source # O(n+m). The intersection with a combining function. let f k al ar = (show k) ++ ":" ++ al ++ "|" ++ ar intersectionWithKey f (fromList [(5, "a"), (3, "b")]) (fromList [(5, "A"), (7, "C")]) == singleton 5 "5:a|A" ## Universal combining function mergeWithKey :: (Key -> a -> b -> Maybe c) -> (IntMap a -> IntMap c) -> (IntMap b -> IntMap c) -> IntMap a -> IntMap b -> IntMap c Source # O(n+m). A high-performance universal combining function. Using mergeWithKey, all combining functions can be defined without any loss of efficiency (with exception of union, difference and intersection, where sharing of some nodes is lost with mergeWithKey). Please make sure you know what is going on when using mergeWithKey, otherwise you can be surprised by unexpected code growth or even corruption of the data structure. When mergeWithKey is given three arguments, it is inlined to the call site. You should therefore use mergeWithKey only to define your custom combining functions. For example, you could define unionWithKey, differenceWithKey and intersectionWithKey as myUnionWithKey f m1 m2 = mergeWithKey (\k x1 x2 -> Just (f k x1 x2)) id id m1 m2 myDifferenceWithKey f m1 m2 = mergeWithKey f id (const empty) m1 m2 myIntersectionWithKey f m1 m2 = mergeWithKey (\k x1 x2 -> Just (f k x1 x2)) (const empty) (const empty) m1 m2 When calling mergeWithKey combine only1 only2, a function combining two IntMaps is created, such that • if a key is present in both maps, it is passed with both corresponding values to the combine function. Depending on the result, the key is either present in the result with specified value, or is left out; • a nonempty subtree present only in the first map is passed to only1 and the output is added to the result; • a nonempty subtree present only in the second map is passed to only2 and the output is added to the result. The only1 and only2 methods must return a map with a subset (possibly empty) of the keys of the given map. The values can be modified arbitrarily. Most common variants of only1 and only2 are id and const empty, but for example map f or filterWithKey f could be used for any f. # Traversal ## Map map :: (a -> b) -> IntMap a -> IntMap b Source # O(n). Map a function over all values in the map. map (++ "x") (fromList [(5,"a"), (3,"b")]) == fromList [(3, "bx"), (5, "ax")] mapWithKey :: (Key -> a -> b) -> IntMap a -> IntMap b Source # O(n). 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")] traverseWithKey :: Applicative t => (Key -> a -> t b) -> IntMap a -> t (IntMap b) Source # O(n). traverseWithKey f s == fromList$ traverse ((k, v) -> (,) k \$ f k v) (toList m) That is, behaves exactly like a regular traverse except that the traversing function also has access to the key associated with a value.

traverseWithKey (\k v -> if odd k then Just (succ v) else Nothing) (fromList [(1, 'a'), (5, 'e')]) == Just (fromList [(1, 'b'), (5, 'f')])
traverseWithKey (\k v -> if odd k then Just (succ v) else Nothing) (fromList [(2, 'c')])           == Nothing

mapAccum :: (a -> b -> (a, c)) -> a -> IntMap b -> (a, IntMap c) Source #

O(n). 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")])

mapAccumWithKey :: (a -> Key -> b -> (a, c)) -> a -> IntMap b -> (a, IntMap c) Source #

O(n). 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")])

mapAccumRWithKey :: (a -> Key -> b -> (a, c)) -> a -> IntMap b -> (a, IntMap c) Source #

O(n). The function mapAccumR threads an accumulating argument through the map in descending order of keys.

mapKeys :: (Key -> Key) -> IntMap a -> IntMap a Source #

O(n*min(n,W)). 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"

mapKeysWith :: (a -> a -> a) -> (Key -> Key) -> IntMap a -> IntMap a Source #

O(n*log n). 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"

mapKeysMonotonic :: (Key -> Key) -> IntMap a -> IntMap a Source #

O(n*min(n,W)). 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")]

# Folds

foldr :: (a -> b -> b) -> b -> IntMap a -> b Source #

O(n). Fold the values in the map using the given right-associative binary operator, such that foldr f z == foldr f z . elems.

For example,

elems map = foldr (:) [] map
let f a len = len + (length a)
foldr f 0 (fromList [(5,"a"), (3,"bbb")]) == 4

foldl :: (a -> b -> a) -> a -> IntMap b -> a Source #

O(n). Fold the values in the map using the given left-associative binary operator, such that foldl f z == foldl f z . elems.

For example,

elems = reverse . foldl (flip (:)) []
let f len a = len + (length a)
foldl f 0 (fromList [(5,"a"), (3,"bbb")]) == 4

foldrWithKey :: (Key -> a -> b -> b) -> b -> IntMap a -> b Source #

O(n). Fold the keys and values in the map using the given right-associative binary operator, such that foldrWithKey f z == foldr (uncurry f) z . toAscList.

For example,

keys map = foldrWithKey (\k x ks -> k:ks) [] map
let f k a result = result ++ "(" ++ (show k) ++ ":" ++ a ++ ")"
foldrWithKey f "Map: " (fromList [(5,"a"), (3,"b")]) == "Map: (5:a)(3:b)"

foldlWithKey :: (a -> Key -> b -> a) -> a -> IntMap b -> a Source #

O(n). Fold the keys and values in the map using the given left-associative binary operator, such that foldlWithKey f z == foldl (\z' (kx, x) -> f z' kx x) z . toAscList.

For example,

keys = reverse . foldlWithKey (\ks k x -> k:ks) []
let f result k a = result ++ "(" ++ (show k) ++ ":" ++ a ++ ")"
foldlWithKey f "Map: " (fromList [(5,"a"), (3,"b")]) == "Map: (3:b)(5:a)"

foldMapWithKey :: Monoid m => (Key -> a -> m) -> IntMap a -> m Source #

O(n). Fold the keys and values in the map using the given monoid, such that

foldMapWithKey f = fold . mapWithKey f

This can be an asymptotically faster than foldrWithKey or foldlWithKey for some monoids.

Since: containers-0.5.4

## Strict folds

foldr' :: (a -> b -> b) -> b -> IntMap a -> b Source #

O(n). A strict version of foldr. Each application of the operator is evaluated before using the result in the next application. This function is strict in the starting value.

foldl' :: (a -> b -> a) -> a -> IntMap b -> a Source #

O(n). A strict version of foldl. Each application of the operator is evaluated before using the result in the next application. This function is strict in the starting value.

foldrWithKey' :: (Key -> a -> b -> b) -> b -> IntMap a -> b Source #

O(n). A strict version of foldrWithKey. Each application of the operator is evaluated before using the result in the next application. This function is strict in the starting value.

foldlWithKey' :: (a -> Key -> b -> a) -> a -> IntMap b -> a Source #

O(n). A strict version of foldlWithKey. Each application of the operator is evaluated before using the result in the next application. This function is strict in the starting value.

# Conversion

elems :: IntMap a -> [a] Source #

O(n). Return all elements of the map in the ascending order of their keys. Subject to list fusion.

elems (fromList [(5,"a"), (3,"b")]) == ["b","a"]
elems empty == []

keys :: IntMap a -> [Key] Source #

O(n). Return all keys of the map in ascending order. Subject to list fusion.

keys (fromList [(5,"a"), (3,"b")]) == [3,5]
keys empty == []

assocs :: IntMap a -> [(Key, a)] Source #

O(n). An alias for toAscList. Returns all key/value pairs in the map in ascending key order. Subject to list fusion.

assocs (fromList [(5,"a"), (3,"b")]) == [(3,"b"), (5,"a")]
assocs empty == []

O(n*min(n,W)). The set of all keys of the map.

keysSet (fromList [(5,"a"), (3,"b")]) == Data.IntSet.fromList [3,5]
keysSet empty == Data.IntSet.empty

fromSet :: (Key -> a) -> IntSet -> IntMap a Source #

O(n). Build a map from a set of keys and a function which for each key computes its value.

fromSet (\k -> replicate k 'a') (Data.IntSet.fromList [3, 5]) == fromList [(5,"aaaaa"), (3,"aaa")]
fromSet undefined Data.IntSet.empty == empty

## Lists

toList :: IntMap a -> [(Key, a)] Source #

O(n). Convert the map to a list of key/value pairs. Subject to list fusion.

toList (fromList [(5,"a"), (3,"b")]) == [(3,"b"), (5,"a")]
toList empty == []

fromList :: [(Key, a)] -> IntMap a Source #

O(n*min(n,W)). Create a map from a list of key/value pairs.

fromList [] == empty
fromList [(5,"a"), (3,"b"), (5, "c")] == fromList [(5,"c"), (3,"b")]
fromList [(5,"c"), (3,"b"), (5, "a")] == fromList [(5,"a"), (3,"b")]

fromListWith :: (a -> a -> a) -> [(Key, a)] -> IntMap a Source #

O(n*min(n,W)). Create a map from a list of key/value pairs with a combining function. See also fromAscListWith.

fromListWith (++) [(5,"a"), (5,"b"), (3,"b"), (3,"a"), (5,"a")] == fromList [(3, "ab"), (5, "aba")]
fromListWith (++) [] == empty

fromListWithKey :: (Key -> a -> a -> a) -> [(Key, a)] -> IntMap a Source #

O(n*min(n,W)). Build a map from a list of key/value pairs with a combining function. See also fromAscListWithKey'.

fromListWith (++) [(5,"a"), (5,"b"), (3,"b"), (3,"a"), (5,"a")] == fromList [(3, "ab"), (5, "aba")]
fromListWith (++) [] == empty

## Ordered lists

toAscList :: IntMap a -> [(Key, a)] Source #

O(n). Convert the map to a list of key/value pairs where the keys are in ascending order. Subject to list fusion.

toAscList (fromList [(5,"a"), (3,"b")]) == [(3,"b"), (5,"a")]

toDescList :: IntMap a -> [(Key, a)] Source #

O(n). Convert the map to a list of key/value pairs where the keys are in descending order. Subject to list fusion.

toDescList (fromList [(5,"a"), (3,"b")]) == [(5,"a"), (3,"b")]

fromAscList :: [(Key, a)] -> IntMap a Source #

O(n). Build a map from a list of key/value pairs where the keys are in ascending order.

fromAscList [(3,"b"), (5,"a")]          == fromList [(3, "b"), (5, "a")]
fromAscList [(3,"b"), (5,"a"), (5,"b")] == fromList [(3, "b"), (5, "b")]

fromAscListWith :: (a -> a -> a) -> [(Key, a)] -> IntMap a Source #

O(n). Build a map from a list of key/value pairs where the keys are in ascending order, with a combining function on equal keys. The precondition (input list is ascending) is not checked.

fromAscListWith (++) [(3,"b"), (5,"a"), (5,"b")] == fromList [(3, "b"), (5, "ba")]

fromAscListWithKey :: (Key -> a -> a -> a) -> [(Key, a)] -> IntMap a Source #

O(n). Build a map from a list of key/value pairs where the keys are in ascending order, with a combining function on equal keys. The precondition (input list is ascending) is not checked.

fromAscListWith (++) [(3,"b"), (5,"a"), (5,"b")] == fromList [(3, "b"), (5, "ba")]

fromDistinctAscList :: [(Key, a)] -> IntMap a Source #

O(n). Build a map from a list of key/value pairs where the keys are in ascending order and all distinct. The precondition (input list is strictly ascending) is not checked.

fromDistinctAscList [(3,"b"), (5,"a")] == fromList [(3, "b"), (5, "a")]

# Filter

filter :: (a -> Bool) -> IntMap a -> IntMap a Source #

O(n). Filter all values that satisfy some predicate.

filter (> "a") (fromList [(5,"a"), (3,"b")]) == singleton 3 "b"
filter (> "x") (fromList [(5,"a"), (3,"b")]) == empty
filter (< "a") (fromList [(5,"a"), (3,"b")]) == empty

filterWithKey :: (Key -> a -> Bool) -> IntMap a -> IntMap a Source #

O(n). Filter all keys/values that satisfy some predicate.

filterWithKey (\k _ -> k > 4) (fromList [(5,"a"), (3,"b")]) == singleton 5 "a"

O(n+m). The restriction of a map to the keys in a set.

m restrictKeys s = filterWithKey (k _ -> k member' s) m


Since: containers-0.5.8

withoutKeys :: IntMap a -> IntSet -> IntMap a Source #

O(n+m). Remove all the keys in a given set from a map.

m withoutKeys s = filterWithKey (k _ -> k notMember' s) m


Since: containers-0.5.8

partition :: (a -> Bool) -> IntMap a -> (IntMap a, IntMap a) Source #

O(n). Partition the map according to some predicate. The first map contains all elements that satisfy the predicate, the second all elements that fail the predicate. See also split.

partition (> "a") (fromList [(5,"a"), (3,"b")]) == (singleton 3 "b", singleton 5 "a")
partition (< "x") (fromList [(5,"a"), (3,"b")]) == (fromList [(3, "b"), (5, "a")], empty)
partition (> "x") (fromList [(5,"a"), (3,"b")]) == (empty, fromList [(3, "b"), (5, "a")])

partitionWithKey :: (Key -> a -> Bool) -> IntMap a -> (IntMap a, IntMap a) Source #

O(n). Partition the map according to some predicate. The first map contains all elements that satisfy the predicate, the second all elements that fail the predicate. See also split.

partitionWithKey (\ k _ -> k > 3) (fromList [(5,"a"), (3,"b")]) == (singleton 5 "a", singleton 3 "b")
partitionWithKey (\ k _ -> k < 7) (fromList [(5,"a"), (3,"b")]) == (fromList [(3, "b"), (5, "a")], empty)
partitionWithKey (\ k _ -> k > 7) (fromList [(5,"a"), (3,"b")]) == (empty, fromList [(3, "b"), (5, "a")])

mapMaybe :: (a -> Maybe b) -> IntMap a -> IntMap b Source #

O(n). 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"

mapMaybeWithKey :: (Key -> a -> Maybe b) -> IntMap a -> IntMap b Source #

O(n). 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"

mapEither :: (a -> Either b c) -> IntMap a -> (IntMap b, IntMap c) Source #

O(n). 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")])

mapEitherWithKey :: (Key -> a -> Either b c) -> IntMap a -> (IntMap b, IntMap c) Source #

O(n). 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")])

split :: Key -> IntMap a -> (IntMap a, IntMap a) Source #

O(min(n,W)). The expression (split k map) is a pair (map1,map2) where all keys in map1 are lower than k and all keys in map2 larger than k. Any key equal to k is found in neither map1 nor map2.

split 2 (fromList [(5,"a"), (3,"b")]) == (empty, fromList [(3,"b"), (5,"a")])
split 3 (fromList [(5,"a"), (3,"b")]) == (empty, singleton 5 "a")
split 4 (fromList [(5,"a"), (3,"b")]) == (singleton 3 "b", singleton 5 "a")
split 5 (fromList [(5,"a"), (3,"b")]) == (singleton 3 "b", empty)
split 6 (fromList [(5,"a"), (3,"b")]) == (fromList [(3,"b"), (5,"a")], empty)

splitLookup :: Key -> IntMap a -> (IntMap a, Maybe a, IntMap a) Source #

O(min(n,W)). Performs a split but also returns whether the pivot key was found in the original map.

splitLookup 2 (fromList [(5,"a"), (3,"b")]) == (empty, Nothing, fromList [(3,"b"), (5,"a")])
splitLookup 3 (fromList [(5,"a"), (3,"b")]) == (empty, Just "b", singleton 5 "a")
splitLookup 4 (fromList [(5,"a"), (3,"b")]) == (singleton 3 "b", Nothing, singleton 5 "a")
splitLookup 5 (fromList [(5,"a"), (3,"b")]) == (singleton 3 "b", Just "a", empty)
splitLookup 6 (fromList [(5,"a"), (3,"b")]) == (fromList [(3,"b"), (5,"a")], Nothing, empty)

splitRoot :: IntMap a -> [IntMap a] Source #

O(1). Decompose a map into pieces based on the structure of the underlying tree. This function is useful for consuming a map in parallel.

No guarantee is made as to the sizes of the pieces; an internal, but deterministic process determines this. However, it is guaranteed that the pieces returned will be in ascending order (all elements in the first submap less than all elements in the second, and so on).

Examples:

splitRoot (fromList (zip [1..6::Int] ['a'..])) ==
[fromList [(1,'a'),(2,'b'),(3,'c')],fromList [(4,'d'),(5,'e'),(6,'f')]]
splitRoot empty == []

Note that the current implementation does not return more than two submaps, but you should not depend on this behaviour because it can change in the future without notice.

# Submap

isSubmapOf :: Eq a => IntMap a -> IntMap a -> Bool Source #

O(n+m). Is this a submap? Defined as (isSubmapOf = isSubmapOfBy (==)).

isSubmapOfBy :: (a -> b -> Bool) -> IntMap a -> IntMap b -> Bool Source #

O(n+m). The expression (isSubmapOfBy f m1 m2) returns True if all keys in m1 are in m2, and when f returns True when applied to their respective values. For example, the following expressions are all True:

isSubmapOfBy (==) (fromList [(1,1)]) (fromList [(1,1),(2,2)])
isSubmapOfBy (<=) (fromList [(1,1)]) (fromList [(1,1),(2,2)])
isSubmapOfBy (==) (fromList [(1,1),(2,2)]) (fromList [(1,1),(2,2)])

But the following are all False:

isSubmapOfBy (==) (fromList [(1,2)]) (fromList [(1,1),(2,2)])
isSubmapOfBy (<) (fromList [(1,1)]) (fromList [(1,1),(2,2)])
isSubmapOfBy (==) (fromList [(1,1),(2,2)]) (fromList [(1,1)])

isProperSubmapOf :: Eq a => IntMap a -> IntMap a -> Bool Source #

O(n+m). Is this a proper submap? (ie. a submap but not equal). Defined as (isProperSubmapOf = isProperSubmapOfBy (==)).

isProperSubmapOfBy :: (a -> b -> Bool) -> IntMap a -> IntMap b -> Bool Source #

O(n+m). Is this a proper submap? (ie. a submap but not equal). The expression (isProperSubmapOfBy f m1 m2) returns True when m1 and m2 are not equal, all keys in m1 are in m2, and when f returns True when applied to their respective values. For example, the following expressions are all True:

isProperSubmapOfBy (==) (fromList [(1,1)]) (fromList [(1,1),(2,2)])
isProperSubmapOfBy (<=) (fromList [(1,1)]) (fromList [(1,1),(2,2)])

But the following are all False:

isProperSubmapOfBy (==) (fromList [(1,1),(2,2)]) (fromList [(1,1),(2,2)])
isProperSubmapOfBy (==) (fromList [(1,1),(2,2)]) (fromList [(1,1)])
isProperSubmapOfBy (<)  (fromList [(1,1)])       (fromList [(1,1),(2,2)])

# Min/Max

lookupMin :: IntMap a -> Maybe (Key, a) Source #

O(min(n,W)). The minimal key of the map. Returns Nothing if the map is empty.

lookupMax :: IntMap a -> Maybe (Key, a) Source #

O(min(n,W)). The maximal key of the map. Returns Nothing if the map is empty.

findMin :: IntMap a -> (Key, a) Source #

O(min(n,W)). The minimal key of the map. Calls error if the map is empty. Use minViewWithKey if the map may be empty.

findMax :: IntMap a -> (Key, a) Source #

O(min(n,W)). The maximal key of the map. Calls error if the map is empty. Use maxViewWithKey if the map may be empty.

deleteMin :: IntMap a -> IntMap a Source #

O(min(n,W)). Delete the minimal key. Returns an empty map if the map is empty.

Note that this is a change of behaviour for consistency with Map – versions prior to 0.5 threw an error if the IntMap was already empty.

deleteMax :: IntMap a -> IntMap a Source #

O(min(n,W)). Delete the maximal key. Returns an empty map if the map is empty.

Note that this is a change of behaviour for consistency with Map – versions prior to 0.5 threw an error if the IntMap was already empty.

deleteFindMin :: IntMap a -> ((Key, a), IntMap a) Source #

O(min(n,W)). Delete and find the minimal element. This function throws an error if the map is empty. Use minViewWithKey if the map may be empty.

deleteFindMax :: IntMap a -> ((Key, a), IntMap a) Source #

O(min(n,W)). Delete and find the maximal element. This function throws an error if the map is empty. Use maxViewWithKey if the map may be empty.

updateMin :: (a -> Maybe a) -> IntMap a -> IntMap a Source #

O(log n). Update the value at the minimal key.

updateMin (\ a -> Just ("X" ++ a)) (fromList [(5,"a"), (3,"b")]) == fromList [(3, "Xb"), (5, "a")]
updateMin (\ _ -> Nothing)         (fromList [(5,"a"), (3,"b")]) == singleton 5 "a"

updateMax :: (a -> Maybe a) -> IntMap a -> IntMap a Source #

O(log n). Update the value at the maximal key.

updateMax (\ a -> Just ("X" ++ a)) (fromList [(5,"a"), (3,"b")]) == fromList [(3, "b"), (5, "Xa")]
updateMax (\ _ -> Nothing)         (fromList [(5,"a"), (3,"b")]) == singleton 3 "b"

updateMinWithKey :: (Key -> a -> Maybe a) -> IntMap a -> IntMap a Source #

O(log n). Update the value at the minimal key.

updateMinWithKey (\ k a -> Just ((show k) ++ ":" ++ a)) (fromList [(5,"a"), (3,"b")]) == fromList [(3,"3:b"), (5,"a")]
updateMinWithKey (\ _ _ -> Nothing)                     (fromList [(5,"a"), (3,"b")]) == singleton 5 "a"

updateMaxWithKey :: (Key -> a -> Maybe a) -> IntMap a -> IntMap a Source #

O(log n). Update the value at the maximal key.

updateMaxWithKey (\ k a -> Just ((show k) ++ ":" ++ a)) (fromList [(5,"a"), (3,"b")]) == fromList [(3,"b"), (5,"5:a")]
updateMaxWithKey (\ _ _ -> Nothing)                     (fromList [(5,"a"), (3,"b")]) == singleton 3 "b"

minView :: IntMap a -> Maybe (a, IntMap a) Source #

O(min(n,W)). Retrieves the minimal key of the map, and the map stripped of that element, or Nothing if passed an empty map.

maxView :: IntMap a -> Maybe (a, IntMap a) Source #

O(min(n,W)). Retrieves the maximal key of the map, and the map stripped of that element, or Nothing if passed an empty map.

minViewWithKey :: IntMap a -> Maybe ((Key, a), IntMap a) Source #

O(min(n,W)). Retrieves the minimal (key,value) pair of the map, and the map stripped of that element, or Nothing if passed an empty map.

minViewWithKey (fromList [(5,"a"), (3,"b")]) == Just ((3,"b"), singleton 5 "a")
minViewWithKey empty == Nothing

maxViewWithKey :: IntMap a -> Maybe ((Key, a), IntMap a) Source #

O(min(n,W)). Retrieves the maximal (key,value) pair of the map, and the map stripped of that element, or Nothing if passed an empty map.

maxViewWithKey (fromList [(5,"a"), (3,"b")]) == Just ((5,"a"), singleton 3 "b")
maxViewWithKey empty == Nothing

# Debugging

showTree :: Show a => IntMap a -> String Source #

Deprecated: These debugging functions will be removed from this module. They are available from Data.IntMap.Internal.Debug.

O(n). Show the tree that implements the map. The tree is shown in a compressed, hanging format.

showTreeWith :: Show a => Bool -> Bool -> IntMap a -> String Source #

Deprecated: These debugging functions will be removed from this module. They are available from Data.IntMap.Internal.Debug.

O(n). The expression (showTreeWith hang wide map) shows the tree that implements the map. If hang is True, a hanging tree is shown otherwise a rotated tree is shown. If wide is True, an extra wide version is shown.