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

Documentation

data HashSet a Source

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

Instances

Foldable HashSet Source
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) Source
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) Source
Methods (==) :: HashSet a -> HashSet a -> Bool (/=) :: HashSet a -> HashSet a -> Bool
(Data a, Eq a, Hashable a) => Data (HashSet a) Source
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) Source
Methods readsPrec :: Int -> ReadS (HashSet a) readList :: ReadS [HashSet a] readPrec :: ReadPrec (HashSet a) readListPrec :: ReadPrec [HashSet a]
Show a => Show (HashSet a) Source
Methods showsPrec :: Int -> HashSet a -> ShowS show :: HashSet a -> String showList :: [HashSet a] -> ShowS
(Hashable a, Eq a) => Monoid (HashSet a) Source
Methods mempty :: HashSet a mappend :: HashSet a -> HashSet a -> HashSet a mconcat :: [HashSet a] -> HashSet a
NFData a => NFData (HashSet a) Source
Methods rnf :: HashSet a -> ()
Hashable a => Hashable (HashSet a) Source
Methods hashWithSalt :: Int -> HashSet a -> Int hash :: HashSet a -> Int
type Item (HashSet a) = a Source

Construction

empty :: HashSet a Source

O(1) Construct an empty set.

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

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

Combine

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

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 Source

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

Basic interface

null :: HashSet a -> Bool Source

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

size :: HashSet a -> Int Source

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

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

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 Source

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

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

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 Source

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 Source

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 Source

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 Source

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 Source

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 Source

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

Conversions

Lists

toList :: HashSet a -> [a] Source

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

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

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

HashMaps

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

O(1) Convert to the equivalent HashMap.

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

O(1) Convert from the equivalent HashMap.