sets.3erl - Man Page

Functions for set manipulation.

Description

Sets are collections of elements with no duplicate elements. The representation of a set is undefined.

This module provides the same interface as the ordsets(3) module but with an undefined representation. One difference is that while this module considers two elements as different if they do not match (=:=), ordsets considers two elements as different if and only if they do not compare equal (==).

Erlang/OTP 24.0 introduced a new internal representation for sets which is more performant. Developers can use this new representation by passing the {version, 2} flag to new/1 and from_list/2, such as sets:new([{version, 2}]). This new representation will become the default in future Erlang/OTP versions. Functions that work on two sets, such as union/2 and similar, will work with sets of different versions. In such cases, there is no guarantee about the version of the returned set. Explicit conversion from the old version to the new one can be done with sets:from_list(sets:to_list(Old), [{version,2}]).

Data Types

set(Element)

As returned by new/0.

set() = set(term())

Exports

add_element(Element, Set1) -> Set2
Types:

Set1 = Set2 = set(Element)

Returns a new set formed from Set1 with Element inserted.

del_element(Element, Set1) -> Set2
Types:

Set1 = Set2 = set(Element)

Returns Set1, but with Element removed.

filter(Pred, Set1) -> Set2
Types:

Pred = fun((Element) -> boolean())
Set1 = Set2 = set(Element)

Filters elements in Set1 with boolean function Pred.

fold(Function, Acc0, Set) -> Acc1
Types:

Function = fun((Element, AccIn) -> AccOut)
Set = set(Element)
Acc0 = Acc1 = AccIn = AccOut = Acc

Folds Function over every element in Set and returns the final value of the accumulator. The evaluation order is undefined.

from_list(List) -> Set
Types:

List = [Element]
Set = set(Element)

Returns a set of the elements in List.

from_list(List, Opts :: [{version, 1..2}]) -> Set
Types:

List = [Element]
Set = set(Element)

Returns a set of the elements in List at the given version.

intersection(SetList) -> Set
Types:

SetList = [set(Element), ...]
Set = set(Element)

Returns the intersection of the non-empty list of sets.

intersection(Set1, Set2) -> Set3
Types:

Set1 = Set2 = Set3 = set(Element)

Returns the intersection of Set1 and Set2.

is_disjoint(Set1, Set2) -> boolean()
Types:

Set1 = Set2 = set(Element)

Returns true if Set1 and Set2 are disjoint (have no elements in common), otherwise false.

is_element(Element, Set) -> boolean()
Types:

Set = set(Element)

Returns true if Element is an element of Set, otherwise false.

is_empty(Set) -> boolean()
Types:

Set = set()

Returns true if Set is an empty set, otherwise false.

is_set(Set) -> boolean()
Types:

Set = term()

Returns true if Set is a set of elements, otherwise false.

is_subset(Set1, Set2) -> boolean()
Types:

Set1 = Set2 = set(Element)

Returns true when every element of Set1 is also a member of Set2, otherwise false.

new() -> set()

Returns a new empty set.

new(Opts :: [{version, 1..2}]) -> set()

Returns a new empty set at the given version.

size(Set) -> integer() >= 0
Types:

Set = set()

Returns the number of elements in Set.

subtract(Set1, Set2) -> Set3
Types:

Set1 = Set2 = Set3 = set(Element)

Returns only the elements of Set1 that are not also elements of Set2.

to_list(Set) -> List
Types:

Set = set(Element)
List = [Element]

Returns the elements of Set as a list. The order of the returned elements is undefined.

union(SetList) -> Set
Types:

SetList = [set(Element)]
Set = set(Element)

Returns the merged (union) set of the list of sets.

union(Set1, Set2) -> Set3
Types:

Set1 = Set2 = Set3 = set(Element)

Returns the merged (union) set of Set1 and Set2.

See Also

gb_sets(3), ordsets(3)

Referenced By

erl_syntax_lib.3erl(3), gb_sets.3erl(3), ordsets.3erl(3), sofs.3erl(3).

stdlib 3.15 Ericsson AB Erlang Module Definition