Data.HashSet

unordered-containers-0.2.7.2: Efficient hashing-based container types

Copyright | 2011 Bryan O'Sullivan
License | BSD-style
Maintainer | johan.tibell@gmail.com
Stability | provisional
Portability | portable
Safe Haskell | Trustworthy
Language | Haskell98

Data.HashSet

Contents

- Construction
- Combine
- Basic interface
- Transformations
- Difference and intersection
- Folds
- Filter
- Conversions
  - Lists
- HashMaps

Description

A set of hashable values. A set cannot contain duplicate items. A `HashSet` makes no guarantees as to the order of its elements.

The implementation is based on hash array mapped trie. A `HashSet` is often faster than other tree-based set types, especially when value 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 HashSet a
- empty :: HashSet a
- singleton :: Hashable a => a -> HashSet a
- union :: (Eq a, Hashable a) => HashSet a -> HashSet a -> HashSet a
- unions :: (Eq a, Hashable a) => [HashSet a] -> HashSet a
- null :: HashSet a -> Bool
- size :: HashSet a -> Int
- member :: (Eq a, Hashable a) => a -> HashSet a -> Bool
- insert :: (Eq a, Hashable a) => a -> HashSet a -> HashSet a
- delete :: (Eq a, Hashable a) => a -> HashSet a -> HashSet a
- map :: (Hashable b, Eq b) => (a -> b) -> HashSet a -> HashSet b
- difference :: (Eq a, Hashable a) => HashSet a -> HashSet a -> HashSet a
- intersection :: (Eq a, Hashable a) => HashSet a -> HashSet a -> HashSet a
- foldl' :: (a -> b -> a) -> a -> HashSet b -> a
- foldr :: (b -> a -> a) -> a -> HashSet b -> a
- filter :: (a -> Bool) -> HashSet a -> HashSet a
- toList :: HashSet a -> [a]
- fromList :: (Eq a, Hashable a) => [a] -> HashSet a
- toMap :: HashSet a -> HashMap a ()
- fromMap :: HashMap a () -> HashSet a

# Documentation

data HashSet a #

A set of values. A set cannot contain duplicate values.

Instances

Foldable HashSet # |
Methods fold :: Monoid m => HashSet m -> m # foldMap :: Monoid m => (a -> m) -> HashSet a -> m # foldr :: (a -> b -> b) -> b -> HashSet a -> b # foldr' :: (a -> b -> b) -> b -> HashSet a -> b # foldl :: (b -> a -> b) -> b -> HashSet a -> b # foldl' :: (b -> a -> b) -> b -> HashSet a -> b # foldr1 :: (a -> a -> a) -> HashSet a -> a # foldl1 :: (a -> a -> a) -> HashSet a -> a # toList :: HashSet a -> [a] # null :: HashSet a -> Bool # length :: HashSet a -> Int # elem :: Eq a => a -> HashSet a -> Bool # maximum :: Ord a => HashSet a -> a # minimum :: Ord a => HashSet a -> a # sum :: Num a => HashSet a -> a # product :: Num a => HashSet a -> a #
(Eq a, Hashable a) => IsList (HashSet a) # |
Associated Types type Item (HashSet a) :: * # Methods fromList :: [Item (HashSet a)] -> HashSet a # fromListN :: Int -> [Item (HashSet a)] -> HashSet a # toList :: HashSet a -> [Item (HashSet a)] #
(Hashable a, Eq a) => Eq (HashSet a) # |
Methods (==) :: HashSet a -> HashSet a -> Bool # (/=) :: HashSet a -> HashSet a -> Bool #
(Data a, Eq a, Hashable a) => Data (HashSet a) # |
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> HashSet a -> c (HashSet a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (HashSet a) # toConstr :: HashSet a -> Constr # dataTypeOf :: HashSet a -> DataType # dataCast1 :: Typeable (* -> *) t => (forall d. Data d => c (t d)) -> Maybe (c (HashSet a)) # dataCast2 :: Typeable (* -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (HashSet a)) # gmapT :: (forall b. Data b => b -> b) -> HashSet a -> HashSet a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> HashSet a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> HashSet a -> r # gmapQ :: (forall d. Data d => d -> u) -> HashSet a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> HashSet a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> HashSet a -> m (HashSet a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> HashSet a -> m (HashSet a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> HashSet a -> m (HashSet a) #
(Eq a, Hashable a, Read a) => Read (HashSet a) # |
Methods readsPrec :: Int -> ReadS (HashSet a) # readList :: ReadS [HashSet a] # readPrec :: ReadPrec (HashSet a) # readListPrec :: ReadPrec [HashSet a] #
Show a => Show (HashSet a) # |
Methods showsPrec :: Int -> HashSet a -> ShowS # show :: HashSet a -> String # showList :: [HashSet a] -> ShowS #
(Hashable a, Eq a) => Semigroup (HashSet a) # |
Methods (<>) :: HashSet a -> HashSet a -> HashSet a # sconcat :: NonEmpty (HashSet a) -> HashSet a # stimes :: Integral b => b -> HashSet a -> HashSet a #
(Hashable a, Eq a) => Monoid (HashSet a) # |
Methods mempty :: HashSet a # mappend :: HashSet a -> HashSet a -> HashSet a # mconcat :: [HashSet a] -> HashSet a #
NFData a => NFData (HashSet a) # |
Methods rnf :: HashSet a -> () #
Hashable a => Hashable (HashSet a) # |
Methods hashWithSalt :: Int -> HashSet a -> Int # hash :: HashSet a -> Int #
type Item (HashSet a) # |
type Item (HashSet a) = a

# Construction

empty :: HashSet a #

O(1) Construct an empty set.

singleton :: Hashable a => a -> HashSet a #

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

# Combine

union :: (Eq a, Hashable a) => HashSet a -> HashSet a -> HashSet a #

O(n+m) Construct a set containing all elements from both sets.

To obtain good performance, the smaller set must be presented as the first argument.

unions :: (Eq a, Hashable a) => [HashSet a] -> HashSet a #

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

# Basic interface

null :: HashSet a -> Bool #

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

size :: HashSet a -> Int #

O(n) Return the number of elements in this set.

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

O(min(n,W)) Return `True` if the given value is present in this set, `False` otherwise.

insert :: (Eq a, Hashable a) => a -> HashSet a -> HashSet a #

O(min(n,W)) Add the specified value to this set.

delete :: (Eq a, Hashable a) => a -> HashSet a -> HashSet a #

O(min(n,W)) Remove the specified value from this set if present.

# Transformations

map :: (Hashable b, Eq b) => (a -> b) -> HashSet a -> HashSet b #

O(n) Transform this set by applying a function to every value. The resulting set may be smaller than the source.

# Difference and intersection

difference :: (Eq a, Hashable a) => HashSet a -> HashSet a -> HashSet a #

O(n) Difference of two sets. Return elements of the first set not existing in the second.

intersection :: (Eq a, Hashable a) => HashSet a -> HashSet a -> HashSet a #

O(n) Intersection of two sets. Return elements present in both the first set and the second.

# Folds

foldl' :: (a -> b -> a) -> a -> HashSet b -> a #

O(n) Reduce this set 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 before using the result in the next application. This function is strict in the starting value.

foldr :: (b -> a -> a) -> a -> HashSet b -> a #

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

# Filter

filter :: (a -> Bool) -> HashSet a -> HashSet a #

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

# Conversions

## Lists

toList :: HashSet a -> [a] #

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

fromList :: (Eq a, Hashable a) => [a] -> HashSet a #

O(n*min(W, n)) Construct a set from a list of elements.

# HashMaps

toMap :: HashSet a -> HashMap a () #

O(1) Convert to the equivalent `HashMap`.

fromMap :: HashMap a () -> HashSet a #

O(1) Convert from the equivalent `HashMap`.