Data.HashMap.Strict

unordered-containers-0.2.10.0: Efficient hashing-based container types

Copyright | 2010-2012 Johan Tibell
License | BSD-style
Maintainer | johan.tibell@gmail.com
Stability | provisional
Portability | portable
Safe Haskell | Safe
Language | Haskell2010

Data.HashMap.Strict

Contents

- Strictness properties
- Construction
- Basic interface
- Combine
  - Union
- Transformations
- Difference and intersection
- Folds
- Filter
- Conversions
  - Lists
  - HashSets

Description

A map from hashable keys to values. A map cannot contain duplicate keys; each key can map to at most one value. A `HashMap` makes no guarantees as to the order of its elements.

The implementation is based on hash array mapped tries. A `HashMap` is often faster than other tree-based set types, especially when key comparison is expensive, as in the case of strings.

Many operations have a average-case complexity of O(log n). The implementation uses a large base (i.e. 16) so in practice these operations are constant time.

Synopsis

- data HashMap k v
- empty :: HashMap k v
- singleton :: Hashable k => k -> v -> HashMap k v
- null :: HashMap k v -> Bool
- size :: HashMap k v -> Int
- member :: (Eq k, Hashable k) => k -> HashMap k a -> Bool
- lookup :: (Eq k, Hashable k) => k -> HashMap k v -> Maybe v
- lookupDefault :: (Eq k, Hashable k) => v -> k -> HashMap k v -> v
- (!) :: (Eq k, Hashable k) => HashMap k v -> k -> v
- insert :: (Eq k, Hashable k) => k -> v -> HashMap k v -> HashMap k v
- insertWith :: (Eq k, Hashable k) => (v -> v -> v) -> k -> v -> HashMap k v -> HashMap k v
- delete :: (Eq k, Hashable k) => k -> HashMap k v -> HashMap k v
- adjust :: (Eq k, Hashable k) => (v -> v) -> k -> HashMap k v -> HashMap k v
- update :: (Eq k, Hashable k) => (a -> Maybe a) -> k -> HashMap k a -> HashMap k a
- alter :: (Eq k, Hashable k) => (Maybe v -> Maybe v) -> k -> HashMap k v -> HashMap k v
- alterF :: (Functor f, Eq k, Hashable k) => (Maybe v -> f (Maybe v)) -> k -> HashMap k v -> f (HashMap k v)
- union :: (Eq k, Hashable k) => HashMap k v -> HashMap k v -> HashMap k v
- unionWith :: (Eq k, Hashable k) => (v -> v -> v) -> HashMap k v -> HashMap k v -> HashMap k v
- unionWithKey :: (Eq k, Hashable k) => (k -> v -> v -> v) -> HashMap k v -> HashMap k v -> HashMap k v
- unions :: (Eq k, Hashable k) => [HashMap k v] -> HashMap k v
- map :: (v1 -> v2) -> HashMap k v1 -> HashMap k v2
- mapWithKey :: (k -> v1 -> v2) -> HashMap k v1 -> HashMap k v2
- traverseWithKey :: Applicative f => (k -> v1 -> f v2) -> HashMap k v1 -> f (HashMap k v2)
- difference :: (Eq k, Hashable k) => HashMap k v -> HashMap k w -> HashMap k v
- differenceWith :: (Eq k, Hashable k) => (v -> w -> Maybe v) -> HashMap k v -> HashMap k w -> HashMap k v
- intersection :: (Eq k, Hashable k) => HashMap k v -> HashMap k w -> HashMap k v
- intersectionWith :: (Eq k, Hashable k) => (v1 -> v2 -> v3) -> HashMap k v1 -> HashMap k v2 -> HashMap k v3
- intersectionWithKey :: (Eq k, Hashable k) => (k -> v1 -> v2 -> v3) -> HashMap k v1 -> HashMap k v2 -> HashMap k v3
- foldl' :: (a -> v -> a) -> a -> HashMap k v -> a
- foldlWithKey' :: (a -> k -> v -> a) -> a -> HashMap k v -> a
- foldr :: (v -> a -> a) -> a -> HashMap k v -> a
- foldrWithKey :: (k -> v -> a -> a) -> a -> HashMap k v -> a
- filter :: (v -> Bool) -> HashMap k v -> HashMap k v
- filterWithKey :: forall k v. (k -> v -> Bool) -> HashMap k v -> HashMap k v
- mapMaybe :: (v1 -> Maybe v2) -> HashMap k v1 -> HashMap k v2
- mapMaybeWithKey :: (k -> v1 -> Maybe v2) -> HashMap k v1 -> HashMap k v2
- keys :: HashMap k v -> [k]
- elems :: HashMap k v -> [v]
- toList :: HashMap k v -> [(k, v)]
- fromList :: (Eq k, Hashable k) => [(k, v)] -> HashMap k v
- fromListWith :: (Eq k, Hashable k) => (v -> v -> v) -> [(k, v)] -> HashMap k v
- keysSet :: HashMap k a -> HashSet k

# Strictness properties

data HashMap k v #

A map from keys to values. A map cannot contain duplicate keys; each key can map to at most one value.

Instances

Eq2 HashMap # |
Instance details Defined in Data.HashMap.Base Methods liftEq2 :: (a -> b -> Bool) -> (c -> d -> Bool) -> HashMap a c -> HashMap b d -> Bool #
Ord2 HashMap # |
Instance details Defined in Data.HashMap.Base Methods liftCompare2 :: (a -> b -> Ordering) -> (c -> d -> Ordering) -> HashMap a c -> HashMap b d -> Ordering #
Show2 HashMap # |
Instance details Defined in Data.HashMap.Base Methods liftShowsPrec2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> (Int -> b -> ShowS) -> ([b] -> ShowS) -> Int -> HashMap a b -> ShowS # liftShowList2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> (Int -> b -> ShowS) -> ([b] -> ShowS) -> [HashMap a b] -> ShowS #
Hashable2 HashMap # |
Instance details Defined in Data.HashMap.Base Methods liftHashWithSalt2 :: (Int -> a -> Int) -> (Int -> b -> Int) -> Int -> HashMap a b -> Int #
Functor (HashMap k) # |
Instance details Defined in Data.HashMap.Base Methods fmap :: (a -> b) -> HashMap k a -> HashMap k b # (<$) :: a -> HashMap k b -> HashMap k a #
Foldable (HashMap k) # |
Instance details Defined in Data.HashMap.Base Methods fold :: Monoid m => HashMap k m -> m # foldMap :: Monoid m => (a -> m) -> HashMap k a -> m # foldr :: (a -> b -> b) -> b -> HashMap k a -> b # foldr' :: (a -> b -> b) -> b -> HashMap k a -> b # foldl :: (b -> a -> b) -> b -> HashMap k a -> b # foldl' :: (b -> a -> b) -> b -> HashMap k a -> b # foldr1 :: (a -> a -> a) -> HashMap k a -> a # foldl1 :: (a -> a -> a) -> HashMap k a -> a # toList :: HashMap k a -> [a] # null :: HashMap k a -> Bool # length :: HashMap k a -> Int # elem :: Eq a => a -> HashMap k a -> Bool # maximum :: Ord a => HashMap k a -> a # minimum :: Ord a => HashMap k a -> a # sum :: Num a => HashMap k a -> a # product :: Num a => HashMap k a -> a #
Traversable (HashMap k) # |
Instance details Defined in Data.HashMap.Base Methods traverse :: Applicative f => (a -> f b) -> HashMap k a -> f (HashMap k b) # sequenceA :: Applicative f => HashMap k (f a) -> f (HashMap k a) # mapM :: Monad m => (a -> m b) -> HashMap k a -> m (HashMap k b) # sequence :: Monad m => HashMap k (m a) -> m (HashMap k a) #
Eq k => Eq1 (HashMap k) # |
Instance details Defined in Data.HashMap.Base Methods liftEq :: (a -> b -> Bool) -> HashMap k a -> HashMap k b -> Bool #
Ord k => Ord1 (HashMap k) # |
Instance details Defined in Data.HashMap.Base Methods liftCompare :: (a -> b -> Ordering) -> HashMap k a -> HashMap k b -> Ordering #
(Eq k, Hashable k, Read k) => Read1 (HashMap k) # |
Instance details Defined in Data.HashMap.Base Methods liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (HashMap k a) # liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [HashMap k a] # liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (HashMap k a) # liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [HashMap k a] #
Show k => Show1 (HashMap k) # |
Instance details Defined in Data.HashMap.Base Methods liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> HashMap k a -> ShowS # liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [HashMap k a] -> ShowS #
Hashable k => Hashable1 (HashMap k) # |
Instance details Defined in Data.HashMap.Base Methods liftHashWithSalt :: (Int -> a -> Int) -> Int -> HashMap k a -> Int #
(Eq k, Hashable k) => IsList (HashMap k v) # |
Instance details Defined in Data.HashMap.Base Associated Types type Item (HashMap k v) :: Type # Methods fromList :: [Item (HashMap k v)] -> HashMap k v # fromListN :: Int -> [Item (HashMap k v)] -> HashMap k v # toList :: HashMap k v -> [Item (HashMap k v)] #
(Eq k, Eq v) => Eq (HashMap k v) # |
Instance details Defined in Data.HashMap.Base Methods (==) :: HashMap k v -> HashMap k v -> Bool # (/=) :: HashMap k v -> HashMap k v -> Bool #
(Data k, Data v, Eq k, Hashable k) => Data (HashMap k v) # |
Instance details Defined in Data.HashMap.Base Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> HashMap k v -> c (HashMap k v) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (HashMap k v) # toConstr :: HashMap k v -> Constr # dataTypeOf :: HashMap k v -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (HashMap k v)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (HashMap k v)) # gmapT :: (forall b. Data b => b -> b) -> HashMap k v -> HashMap k v # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> HashMap k v -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> HashMap k v -> r # gmapQ :: (forall d. Data d => d -> u) -> HashMap k v -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> HashMap k v -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> HashMap k v -> m (HashMap k v) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> HashMap k v -> m (HashMap k v) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> HashMap k v -> m (HashMap k v) #
(Ord k, Ord v) => Ord (HashMap k v) # | The order is total. Note: Because the hash is not guaranteed to be stable across library versions, OSes, or architectures, neither is an actual order of elements in `HashMap` or an result of `compare`.is stable.
Instance details Defined in Data.HashMap.Base Methods compare :: HashMap k v -> HashMap k v -> Ordering # (<) :: HashMap k v -> HashMap k v -> Bool # (<=) :: HashMap k v -> HashMap k v -> Bool # (>) :: HashMap k v -> HashMap k v -> Bool # (>=) :: HashMap k v -> HashMap k v -> Bool # max :: HashMap k v -> HashMap k v -> HashMap k v # min :: HashMap k v -> HashMap k v -> HashMap k v #
(Eq k, Hashable k, Read k, Read e) => Read (HashMap k e) # |
Instance details Defined in Data.HashMap.Base Methods readsPrec :: Int -> ReadS (HashMap k e) # readList :: ReadS [HashMap k e] # readPrec :: ReadPrec (HashMap k e) # readListPrec :: ReadPrec [HashMap k e] #
(Show k, Show v) => Show (HashMap k v) # |
Instance details Defined in Data.HashMap.Base Methods showsPrec :: Int -> HashMap k v -> ShowS # show :: HashMap k v -> String # showList :: [HashMap k v] -> ShowS #
(Eq k, Hashable k) => Semigroup (HashMap k v) # |
Instance details Defined in Data.HashMap.Base Methods (<>) :: HashMap k v -> HashMap k v -> HashMap k v # sconcat :: NonEmpty (HashMap k v) -> HashMap k v # stimes :: Integral b => b -> HashMap k v -> HashMap k v #
(Eq k, Hashable k) => Monoid (HashMap k v) # |
Instance details Defined in Data.HashMap.Base Methods mempty :: HashMap k v # mappend :: HashMap k v -> HashMap k v -> HashMap k v # mconcat :: [HashMap k v] -> HashMap k v #
(NFData k, NFData v) => NFData (HashMap k v) # |
Instance details Defined in Data.HashMap.Base Methods rnf :: HashMap k v -> () #
(Hashable k, Hashable v) => Hashable (HashMap k v) # |
Instance details Defined in Data.HashMap.Base Methods hashWithSalt :: Int -> HashMap k v -> Int # hash :: HashMap k v -> Int #
type Item (HashMap k v) # |
Instance details Defined in Data.HashMap.Base type Item (HashMap k v) = (k, v)

# Construction

empty :: HashMap k v #

O(1) Construct an empty map.

singleton :: Hashable k => k -> v -> HashMap k v #

O(1) Construct a map with a single element.

# Basic interface

null :: HashMap k v -> Bool #

O(1) Return `True` if this map is empty, `False` otherwise.

size :: HashMap k v -> Int #

O(n) Return the number of key-value mappings in this map.

member :: (Eq k, Hashable k) => k -> HashMap k a -> Bool #

O(log n) Return `True` if the specified key is present in the map, `False` otherwise.

lookup :: (Eq k, Hashable k) => k -> HashMap k v -> Maybe v #

O(log n) Return the value to which the specified key is mapped, or `Nothing` if this map contains no mapping for the key.

lookupDefault #

Arguments

:: (Eq k, Hashable k) |
=> v | Default value to return.
-> k |
-> HashMap k v |
-> v |

O(log n) Return the value to which the specified key is mapped, or the default value if this map contains no mapping for the key.

(!) :: (Eq k, Hashable k) => HashMap k v -> k -> v infixl 9 #

O(log n) Return the value to which the specified key is mapped. Calls `error` if this map contains no mapping for the key.

insert :: (Eq k, Hashable k) => k -> v -> HashMap k v -> HashMap k v #

O(log n) Associate the specified value with the specified key in this map. If this map previously contained a mapping for the key, the old value is replaced.

insertWith :: (Eq k, Hashable k) => (v -> v -> v) -> k -> v -> HashMap k v -> HashMap k v #

O(log n) Associate the value with the key in this map. If this map previously contained a mapping for the key, the old value is replaced by the result of applying the given function to the new and old value. Example:

    insertWith f k v map
      where f new old = new + old

delete :: (Eq k, Hashable k) => k -> HashMap k v -> HashMap k v #

O(log n) Remove the mapping for the specified key from this map if present.

adjust :: (Eq k, Hashable k) => (v -> v) -> k -> HashMap k v -> HashMap k v #

O(log n) Adjust the value tied to a given key in this map only if it is present. Otherwise, leave the map alone.

update :: (Eq k, Hashable k) => (a -> Maybe a) -> k -> HashMap k a -> HashMap k a #

O(log n) 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.

alter :: (Eq k, Hashable k) => (Maybe v -> Maybe v) -> k -> HashMap k v -> HashMap k v #

O(log n) 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 a map. In short : ``lookup` k (`alter` f k m) = f (`lookup` k m)`.

alterF :: (Functor f, Eq k, Hashable k) => (Maybe v -> f (Maybe v)) -> k -> HashMap k v -> f (HashMap k v) #

O(log n) The expression (``alterF` f k map`) alters the value `x` at `k`, or absence thereof. `alterF` can be used to insert, delete, or update a value in a map.

Note: `alterF` is a flipped version of the `at` combinator from Control.Lens.At.

Since: 0.2.9

# Combine

## Union

union :: (Eq k, Hashable k) => HashMap k v -> HashMap k v -> HashMap k v #

O(n+m) The union of two maps. If a key occurs in both maps, the mapping from the first will be the mapping in the result.

unionWith :: (Eq k, Hashable k) => (v -> v -> v) -> HashMap k v -> HashMap k v -> HashMap k v #

O(n+m) The union of two maps. If a key occurs in both maps, the provided function (first argument) will be used to compute the result.

unionWithKey :: (Eq k, Hashable k) => (k -> v -> v -> v) -> HashMap k v -> HashMap k v -> HashMap k v #

O(n+m) The union of two maps. If a key occurs in both maps, the provided function (first argument) will be used to compute the result.

unions :: (Eq k, Hashable k) => [HashMap k v] -> HashMap k v #

Construct a set containing all elements from a list of sets.

# Transformations

map :: (v1 -> v2) -> HashMap k v1 -> HashMap k v2 #

O(n) Transform this map by applying a function to every value.

mapWithKey :: (k -> v1 -> v2) -> HashMap k v1 -> HashMap k v2 #

O(n) Transform this map by applying a function to every value.

traverseWithKey :: Applicative f => (k -> v1 -> f v2) -> HashMap k v1 -> f (HashMap k v2) #

O(n) Perform an `Applicative` action for each key-value pair in a `HashMap` and produce a `HashMap` of all the results. Each `HashMap` will be strict in all its values.

    traverseWithKey f = fmap (map id) . Data.HashMap.Lazy.traverseWithKey f

Note: the order in which the actions occur is unspecified. In particular, when the map contains hash collisions, the order in which the actions associated with the keys involved will depend in an unspecified way on their insertion order.

# Difference and intersection

difference :: (Eq k, Hashable k) => HashMap k v -> HashMap k w -> HashMap k v #

O(n*log m) Difference of two maps. Return elements of the first map not existing in the second.

differenceWith :: (Eq k, Hashable k) => (v -> w -> Maybe v) -> HashMap k v -> HashMap k w -> HashMap k v #

O(n*log m) Difference with a combining function. When two equal keys are encountered, the combining function is applied to the values of these keys. 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`.

intersection :: (Eq k, Hashable k) => HashMap k v -> HashMap k w -> HashMap k v #

O(n*log m) Intersection of two maps. Return elements of the first map for keys existing in the second.

intersectionWith :: (Eq k, Hashable k) => (v1 -> v2 -> v3) -> HashMap k v1 -> HashMap k v2 -> HashMap k v3 #

O(n+m) Intersection of two maps. If a key occurs in both maps the provided function is used to combine the values from the two maps.

intersectionWithKey :: (Eq k, Hashable k) => (k -> v1 -> v2 -> v3) -> HashMap k v1 -> HashMap k v2 -> HashMap k v3 #

O(n+m) Intersection of two maps. If a key occurs in both maps the provided function is used to combine the values from the two maps.

# Folds

foldl' :: (a -> v -> a) -> a -> HashMap k v -> a #

O(n) Reduce this map by applying a binary operator to all elements, using the given starting value (typically the left-identity of the operator). 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 -> k -> v -> a) -> a -> HashMap k v -> a #

O(n) Reduce this map by applying a binary operator to all elements, using the given starting value (typically the left-identity of the operator). Each application of the operator is evaluated before using the result in the next application. This function is strict in the starting value.

foldr :: (v -> a -> a) -> a -> HashMap k v -> a #

O(n) Reduce this map by applying a binary operator to all elements, using the given starting value (typically the right-identity of the operator).

foldrWithKey :: (k -> v -> a -> a) -> a -> HashMap k v -> a #

O(n) Reduce this map by applying a binary operator to all elements, using the given starting value (typically the right-identity of the operator).

# Filter

filter :: (v -> Bool) -> HashMap k v -> HashMap k v #

O(n) Filter this map by retaining only elements which values satisfy a predicate.

filterWithKey :: forall k v. (k -> v -> Bool) -> HashMap k v -> HashMap k v #

O(n) Filter this map by retaining only elements satisfying a predicate.

mapMaybe :: (v1 -> Maybe v2) -> HashMap k v1 -> HashMap k v2 #

O(n) Transform this map by applying a function to every value and retaining only some of them.

mapMaybeWithKey :: (k -> v1 -> Maybe v2) -> HashMap k v1 -> HashMap k v2 #

O(n) Transform this map by applying a function to every value and retaining only some of them.

# Conversions

keys :: HashMap k v -> [k] #

O(n) Return a list of this map's keys. The list is produced lazily.

elems :: HashMap k v -> [v] #

O(n) Return a list of this map's values. The list is produced lazily.

## Lists

toList :: HashMap k v -> [(k, v)] #

O(n) Return a list of this map's elements. The list is produced lazily. The order of its elements is unspecified.

fromList :: (Eq k, Hashable k) => [(k, v)] -> HashMap k v #

O(n*log n) Construct a map with the supplied mappings. If the list contains duplicate mappings, the later mappings take precedence.

fromListWith :: (Eq k, Hashable k) => (v -> v -> v) -> [(k, v)] -> HashMap k v #

O(n*log n) Construct a map from a list of elements. Uses the provided function f to merge duplicate entries (f newVal oldVal).

For example:

    fromListWith (+) [ (x, 1) | x <- xs ]

will create a map with number of occurrences of each element in xs.

    fromListWith (++) [ (k, [v]) | (k, v) <- xs ]

will group all values by their keys in a list 'xs :: [(k, v)]' and return a 'HashMap k [v]'.

## HashSets

keysSet :: HashMap k a -> HashSet k #

O(n) Produce a `HashSet` of all the keys in the given `HashMap`.

Since: 0.2.10.0