sets (stdlib v3.15.2)
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}]).
See Also
Link to this section Summary
Functions
Returns a new set formed from Set1 with Element inserted.
Returns Set1, but with Element removed.
Filters elements in Set1 with boolean function Pred.
Folds Function over every element in Set and returns the final value of the accumulator. The evaluation order is undefined.
Returns a set of the elements in List.
Returns a set of the elements in List at the given version.
Returns the intersection of the non-empty list of sets.
Returns the intersection of Set1 and Set2.
Returns true if Set1 and Set2 are disjoint (have no elements in common), otherwise false.
Returns true if Element is an element of Set, otherwise false.
Returns true if Set is an empty set, otherwise false.
Returns true if Set is a set of elements, otherwise false.
Returns true when every element of Set1 is also a member of Set2, otherwise false.
Returns a new empty set.
Returns a new empty set at the given version.
Returns the number of elements in Set.
Returns only the elements of Set1 that are not also elements of Set2.
Returns the elements of Set as a list. The order of the returned elements is undefined.
Returns the merged (union) set of the list of sets.
Returns the merged (union) set of Set1 and Set2.
Link to this section Types
-type set() :: term().
Specs
set() :: set(_).
Specs
set(Element)
As returned by new/0.
Link to this section Functions
add_element/2
Specs
Returns a new set formed from Set1 with Element inserted.
del_element/2
Specs
Returns Set1, but with Element removed.
filter/2
Specs
filter(Pred, Set1) -> Set2
when Pred :: fun((Element) -> boolean()), Set1 :: set(Element), Set2 :: set(Element).
Filters elements in Set1 with boolean function Pred.
fold/3
Specs
fold(Function, Acc0, Set) -> Acc1
when
Function :: fun((Element, AccIn) -> AccOut),
Set :: set(Element),
Acc0 :: Acc,
Acc1 :: Acc,
AccIn :: Acc,
AccOut :: Acc.
Folds Function over every element in Set and returns the final value of the accumulator. The evaluation order is undefined.
from_list/1
Specs
from_list(List) -> Set when List :: [Element], Set :: set(Element).
Returns a set of the elements in List.
Specs
from_list(List, [{version, 1..2}]) -> Set when List :: [Element], Set :: set(Element).
Returns a set of the elements in List at the given version.
intersection/1
Specs
Returns the intersection of the non-empty list of sets.
intersection/2
Specs
intersection(Set1, Set2) -> Set3
when Set1 :: set(Element), Set2 :: set(Element), Set3 :: set(Element).
Returns the intersection of Set1 and Set2.
is_disjoint/2
Specs
Returns true if Set1 and Set2 are disjoint (have no elements in common), otherwise false.
is_element/2
Specs
is_element(Element, Set) -> boolean() when Set :: set(Element).
Returns true if Element is an element of Set, otherwise false.
Specs
is_empty(Set) -> boolean() when Set :: set().
Returns true if Set is an empty set, otherwise false.
is_set/1
Specs
is_set(Set) -> boolean() when Set :: term().
Returns true if Set is a set of elements, otherwise false.
is_subset/2
Specs
Returns true when every element of Set1 is also a member of Set2, otherwise false.
new/0
Specs
new() -> set().
Returns a new empty set.
Specs
new([{version, 1..2}]) -> set().
Returns a new empty set at the given version.
size/1
Specs
size(Set) -> non_neg_integer() when Set :: set().
Returns the number of elements in Set.
subtract/2
Specs
Returns only the elements of Set1 that are not also elements of Set2.
to_list/1
Specs
to_list(Set) -> List when Set :: set(Element), List :: [Element].
Returns the elements of Set as a list. The order of the returned elements is undefined.
union/1
Specs
Returns the merged (union) set of the list of sets.
union/2
Specs
Returns the merged (union) set of Set1 and Set2.