GHC.Data.Word64Set.Internal

WARNING

This module is considered internal.

The Package Versioning Policy does not apply.

The contents of this module may change in any way whatsoever and without any warning between minor versions of this package.

Authors importing this module are expected to track development closely.

Description

An efficient implementation of integer sets.

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

 import Data.Word64Set (Word64Set)
 import qualified Data.Word64Set as Word64Set

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 set implementation (see Data.Set).

• Chris Okasaki and Andy Gill, "Fast Mergeable Integer Maps", Workshop on ML, September 1998, pages 77-86, http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.37.5452
• D.R. Morrison, "PATRICIA -- Practical Algorithm To Retrieve Information Coded In Alphanumeric", Journal of the ACM, 15(4), October 1968, pages 514-534.

Additionally, this implementation places bitmaps in the leaves of the tree. Their size is the natural size of a machine word (32 or 64 bits) and greatly reduce memory footprint and execution times for dense sets, e.g. sets where it is likely that many values lie close to each other. The asymptotics are not affected by this optimization.

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).

Since: 0.5.9

Set type

data Word64Set

A set of integers.

Constructors

Bin !Prefix !Mask !Word64Set !Word64Set

Tip !Prefix !BitMap

Nil

Instances

Data Word64Set

Defined in GHC.Data.Word64Set.Internal

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Word64Set -> c Word64Set

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Word64Set

toConstr :: Word64Set -> Constr

dataTypeOf :: Word64Set -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Word64Set)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Word64Set)

gmapT :: (forall b. Data b => b -> b) -> Word64Set -> Word64Set

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Word64Set -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Word64Set -> r

gmapQ :: (forall d. Data d => d -> u) -> Word64Set -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> Word64Set -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Word64Set -> m Word64Set

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Word64Set -> m Word64Set

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Word64Set -> m Word64Set

Monoid Word64Set

Defined in GHC.Data.Word64Set.Internal

Methods

mempty :: Word64Set

mappend :: Word64Set -> Word64Set -> Word64Set

mconcat :: [Word64Set] -> Word64Set

Semigroup Word64Set

Since: 0.5.7

Defined in GHC.Data.Word64Set.Internal

Methods

(<>) :: Word64Set -> Word64Set -> Word64Set

sconcat :: NonEmpty Word64Set -> Word64Set

stimes :: Integral b => b -> Word64Set -> Word64Set

IsList Word64Set

Since: 0.5.6.2

Defined in GHC.Data.Word64Set.Internal

Associated Types

type Item Word64Set

Methods

fromList :: [Item Word64Set] -> Word64Set

fromListN :: Int -> [Item Word64Set] -> Word64Set

toList :: Word64Set -> [Item Word64Set]

Read Word64Set

Defined in GHC.Data.Word64Set.Internal

Methods

readsPrec :: Int -> ReadS Word64Set

readList :: ReadS [Word64Set]

readPrec :: ReadPrec Word64Set

readListPrec :: ReadPrec [Word64Set]

Show Word64Set

Defined in GHC.Data.Word64Set.Internal

Methods

showsPrec :: Int -> Word64Set -> ShowS

show :: Word64Set -> String

showList :: [Word64Set] -> ShowS

NFData Word64Set

Defined in GHC.Data.Word64Set.Internal

Methods

rnf :: Word64Set -> ()

Outputable Word64Set

Defined in GHC.Utils.Outputable

Methods

ppr :: Word64Set -> SDoc

Eq Word64Set

Defined in GHC.Data.Word64Set.Internal

Methods

(==) :: Word64Set -> Word64Set -> Bool

(/=) :: Word64Set -> Word64Set -> Bool

Ord Word64Set

Defined in GHC.Data.Word64Set.Internal

Methods

compare :: Word64Set -> Word64Set -> Ordering

(<) :: Word64Set -> Word64Set -> Bool

(<=) :: Word64Set -> Word64Set -> Bool

(>) :: Word64Set -> Word64Set -> Bool

(>=) :: Word64Set -> Word64Set -> Bool

max :: Word64Set -> Word64Set -> Word64Set

min :: Word64Set -> Word64Set -> Word64Set

type Item Word64Set

Defined in GHC.Data.Word64Set.Internal

type Item Word64Set = Key

type Key = Word64

type Prefix = Word64

type Mask = Word64

type BitMap = Word64

Operators

(\\) :: Word64Set -> Word64Set -> Word64Set infixl 9

\(O(n+m)\). See difference.

Query

null :: Word64Set -> Bool

\(O(1)\). Is the set empty?

size :: Word64Set -> Int

\(O(n)\). Cardinality of the set.

member :: Key -> Word64Set -> Bool

\(O(\min(n,W))\). Is the value a member of the set?

notMember :: Key -> Word64Set -> Bool

\(O(\min(n,W))\). Is the element not in the set?

lookupLT :: Key -> Word64Set -> Maybe Key

\(O(\min(n,W))\). Find largest element smaller than the given one.

lookupLT 3 (fromList [3, 5]) == Nothing
lookupLT 5 (fromList [3, 5]) == Just 3

lookupGT :: Key -> Word64Set -> Maybe Key

\(O(\min(n,W))\). Find smallest element greater than the given one.

lookupGT 4 (fromList [3, 5]) == Just 5
lookupGT 5 (fromList [3, 5]) == Nothing

lookupLE :: Key -> Word64Set -> Maybe Key

\(O(\min(n,W))\). Find largest element smaller or equal to the given one.

lookupLE 2 (fromList [3, 5]) == Nothing
lookupLE 4 (fromList [3, 5]) == Just 3
lookupLE 5 (fromList [3, 5]) == Just 5

lookupGE :: Key -> Word64Set -> Maybe Key

\(O(\min(n,W))\). Find smallest element greater or equal to the given one.

lookupGE 3 (fromList [3, 5]) == Just 3
lookupGE 4 (fromList [3, 5]) == Just 5
lookupGE 6 (fromList [3, 5]) == Nothing

isSubsetOf :: Word64Set -> Word64Set -> Bool

\(O(n+m)\). Is this a subset? (s1 `isSubsetOf` s2) tells whether s1 is a subset of s2.

isProperSubsetOf :: Word64Set -> Word64Set -> Bool

\(O(n+m)\). Is this a proper subset? (ie. a subset but not equal).

disjoint :: Word64Set -> Word64Set -> Bool

\(O(n+m)\). Check whether two sets are disjoint (i.e. their intersection is empty).

disjoint (fromList [2,4,6])   (fromList [1,3])     == True
disjoint (fromList [2,4,6,8]) (fromList [2,3,5,7]) == False
disjoint (fromList [1,2])     (fromList [1,2,3,4]) == False
disjoint (fromList [])        (fromList [])        == True

Since: 0.5.11

Construction

empty :: Word64Set

\(O(1)\). The empty set.

singleton :: Key -> Word64Set

\(O(1)\). A set of one element.

insert :: Key -> Word64Set -> Word64Set

\(O(\min(n,W))\). Add a value to the set. There is no left- or right bias for Word64Sets.

delete :: Key -> Word64Set -> Word64Set

\(O(\min(n,W))\). Delete a value in the set. Returns the original set when the value was not present.

alterF :: Functor f => (Bool -> f Bool) -> Key -> Word64Set -> f Word64Set

\(O(\min(n,W))\). (alterF f x s) can delete or insert x in s depending on whether it is already present in s.

In short:

member x <$> alterF f x s = f (member x s)

Note: alterF is a variant of the at combinator from Control.Lens.At.

Since: 0.6.3.1

Combine

union :: Word64Set -> Word64Set -> Word64Set

\(O(n+m)\). The union of two sets.

unions :: Foldable f => f Word64Set -> Word64Set

The union of a list of sets.

difference :: Word64Set -> Word64Set -> Word64Set

\(O(n+m)\). Difference between two sets.

intersection :: Word64Set -> Word64Set -> Word64Set

\(O(n+m)\). The intersection of two sets.

Filter

filter :: (Key -> Bool) -> Word64Set -> Word64Set

\(O(n)\). Filter all elements that satisfy some predicate.

partition :: (Key -> Bool) -> Word64Set -> (Word64Set, Word64Set)

\(O(n)\). partition the set according to some predicate.

takeWhileAntitone :: (Key -> Bool) -> Word64Set -> Word64Set

\(O(\min(n,W))\). Take while a predicate on the elements holds. The user is responsible for ensuring that for all Ints, j < k ==> p j >= p k. See note at spanAntitone.

takeWhileAntitone p = fromDistinctAscList . takeWhile p . toList
takeWhileAntitone p = filter p

Since: 0.6.7

dropWhileAntitone :: (Key -> Bool) -> Word64Set -> Word64Set

\(O(\min(n,W))\). Drop while a predicate on the elements holds. The user is responsible for ensuring that for all Ints, j < k ==> p j >= p k. See note at spanAntitone.

dropWhileAntitone p = fromDistinctAscList . dropWhile p . toList
dropWhileAntitone p = filter (not . p)

Since: 0.6.7

spanAntitone :: (Key -> Bool) -> Word64Set -> (Word64Set, Word64Set)

\(O(\min(n,W))\). Divide a set at the point where a predicate on the elements stops holding. The user is responsible for ensuring that for all Ints, j < k ==> p j >= p k.

spanAntitone p xs = (takeWhileAntitone p xs, dropWhileAntitone p xs)
spanAntitone p xs = partition p xs

Note: if p is not actually antitone, then spanAntitone will split the set at some unspecified point.

Since: 0.6.7

split :: Key -> Word64Set -> (Word64Set, Word64Set)

\(O(\min(n,W))\). The expression (split x set) is a pair (set1,set2) where set1 comprises the elements of set less than x and set2 comprises the elements of set greater than x.

split 3 (fromList [1..5]) == (fromList [1,2], fromList [4,5])

splitMember :: Key -> Word64Set -> (Word64Set, Bool, Word64Set)

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

splitRoot :: Word64Set -> [Word64Set]

\(O(1)\). Decompose a set into pieces based on the structure of the underlying tree. This function is useful for consuming a set 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 [1..120]) == [fromList [1..63],fromList [64..120]]
splitRoot empty == []

Note that the current implementation does not return more than two subsets, but you should not depend on this behaviour because it can change in the future without notice. Also, the current version does not continue splitting all the way to individual singleton sets -- it stops at some point.

Map

map :: (Key -> Key) -> Word64Set -> Word64Set

\(O(n \min(n,W))\). map f s is the set obtained by applying f to each element of s.

It's worth noting that the size of the result may be smaller if, for some (x,y), x /= y && f x == f y

mapMonotonic :: (Key -> Key) -> Word64Set -> Word64Set

\(O(n)\). The

mapMonotonic f s == map f s, but works only when f is strictly increasing. The precondition is not checked. Semi-formally, we have:

and [x < y ==> f x < f y | x <- ls, y <- ls]
                    ==> mapMonotonic f s == map f s
    where ls = toList s

Since: 0.6.3.1

Folds

foldr :: (Key -> b -> b) -> b -> Word64Set -> b

\(O(n)\). Fold the elements in the set using the given right-associative binary operator, such that foldr f z == foldr f z . toAscList.

For example,

toAscList set = foldr (:) [] set

foldl :: (a -> Key -> a) -> a -> Word64Set -> a

\(O(n)\). Fold the elements in the set using the given left-associative binary operator, such that foldl f z == foldl f z . toAscList.

For example,

toDescList set = foldl (flip (:)) [] set

Strict folds

foldr' :: (Key -> b -> b) -> b -> Word64Set -> b

\(O(n)\). 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 -> Key -> a) -> a -> Word64Set -> a

\(O(n)\). 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.

Legacy folds

fold :: (Key -> b -> b) -> b -> Word64Set -> b

\(O(n)\). Fold the elements in the set using the given right-associative binary operator. This function is an equivalent of foldr and is present for compatibility only.

Please note that fold will be deprecated in the future and removed.

Min/Max

findMin :: Word64Set -> Key

\(O(\min(n,W))\). The minimal element of the set.

findMax :: Word64Set -> Key

\(O(\min(n,W))\). The maximal element of a set.

deleteMin :: Word64Set -> Word64Set

\(O(\min(n,W))\). Delete the minimal element. Returns an empty set if the set is empty.

Note that this is a change of behaviour for consistency with Set – versions prior to 0.5 threw an error if the Word64Set was already empty.

deleteMax :: Word64Set -> Word64Set

\(O(\min(n,W))\). Delete the maximal element. Returns an empty set if the set is empty.

Note that this is a change of behaviour for consistency with Set – versions prior to 0.5 threw an error if the Word64Set was already empty.

deleteFindMin :: Word64Set -> (Key, Word64Set)

\(O(\min(n,W))\). Delete and find the minimal element.

deleteFindMin set = (findMin set, deleteMin set)

deleteFindMax :: Word64Set -> (Key, Word64Set)

\(O(\min(n,W))\). Delete and find the maximal element.

deleteFindMax set = (findMax set, deleteMax set)

maxView :: Word64Set -> Maybe (Key, Word64Set)

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

minView :: Word64Set -> Maybe (Key, Word64Set)

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

Conversion

List

elems :: Word64Set -> [Key]

\(O(n)\). An alias of toAscList. The elements of a set in ascending order. Subject to list fusion.

toList :: Word64Set -> [Key]

\(O(n)\). Convert the set to a list of elements. Subject to list fusion.

fromList :: [Key] -> Word64Set

\(O(n \min(n,W))\). Create a set from a list of integers.

Ordered list

toAscList :: Word64Set -> [Key]

\(O(n)\). Convert the set to an ascending list of elements. Subject to list fusion.

toDescList :: Word64Set -> [Key]

\(O(n)\). Convert the set to a descending list of elements. Subject to list fusion.

fromAscList :: [Key] -> Word64Set

\(O(n)\). Build a set from an ascending list of elements. The precondition (input list is ascending) is not checked.

fromDistinctAscList :: [Key] -> Word64Set

\(O(n)\). Build a set from an ascending list of distinct elements. The precondition (input list is strictly ascending) is not checked.

Debugging

showTree :: Word64Set -> String

\(O(n \min(n,W))\). Show the tree that implements the set. The tree is shown in a compressed, hanging format.

showTreeWith :: Bool -> Bool -> Word64Set -> String

\(O(n \min(n,W))\). The expression (showTreeWith hang wide map) shows the tree that implements the set. 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.

Internals

match :: Word64 -> Prefix -> Mask -> Bool

suffixBitMask :: Word64

prefixBitMask :: Word64

bitmapOf :: Word64 -> BitMap

zero :: Word64 -> Mask -> Bool