ordsets(3erl)

NAME
ordsets - Functions for manipulating sets as ordered lists.

DESCRIPTION

Sets are collections of elements with no duplicate elements. An ordset is a representation of a set, where an ordered list is used to store the elements of the set. An ordered list is more efficient than an unordered list. Elements are ordered according to the Erlang term order.

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

DATA TYPES

ordset(T) = [T]

    As returned by new/0.

EXPORTS

add_element(Element, Ordset1) -> Ordset2

    Types:

        Element = E
        Ordset1 = ordset(T)
        Ordset2 = ordset(T | E)

    Returns a new ordered set formed from Ordset1 with Element inserted.

del_element(Element, Ordset1) -> Ordset2

    Types:

        Element = term()
        Ordset1 = Ordset2 = ordset(T)

    Returns Ordset1, but with Element removed.

filter(Pred, Ordset1) -> Ordset2

    Types:

        Pred = fun((Element :: T) -> boolean())
        Ordset1 = Ordset2 = ordset(T)

    Filters elements in Ordset1 with boolean function Pred.

fold(Function, Acc0, Ordset) -> Acc1

    Types:

        Function =
            fun((Element :: T, AccIn :: term()) -> AccOut :: term())
        Ordset = ordset(T)
        Acc0 = Acc1 = term()

    Folds Function over every element in Ordset and returns the final value of the accumulator.

from_list(List) -> Ordset

    Types:

        List = [T]
        Ordset = ordset(T)

    Returns an ordered set of the elements in List.

intersection(OrdsetList) -> Ordset

    Types:

        OrdsetList = [ordset(term()), ...]
        Ordset = ordset(term())

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

intersection(Ordset1, Ordset2) -> Ordset3

    Types:

        Ordset1 = Ordset2 = Ordset3 = ordset(term())

    Returns the intersection of Ordset1 and Ordset2.

is_disjoint(Ordset1, Ordset2) -> boolean()

    Types:

        Ordset1 = Ordset2 = ordset(term())

    Returns true if Ordset1 and Ordset2 are disjoint (have no elements in common), otherwise false.

is_element(Element, Ordset) -> boolean()

    Types:

        Element = term()
        Ordset = ordset(term())

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

is_empty(Ordset) -> boolean()

    Types:

        Ordset = ordset(term())

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

is_set(Ordset) -> boolean()

    Types:

        Ordset = term()

    Returns true if Ordset is an ordered set of elements, otherwise false. This function will return true for any ordered list, even when not constructed by the functions in this module.

is_subset(Ordset1, Ordset2) -> boolean()

    Types:

        Ordset1 = Ordset2 = ordset(term())

    Returns true when every element of Ordset1 is also a member of Ordset2, otherwise false.

new() -> []

    Returns a new empty ordered set.

size(Ordset) -> integer() >= 0

    Types:

        Ordset = ordset(term())

    Returns the number of elements in Ordset.

subtract(Ordset1, Ordset2) -> Ordset3

    Types:

        Ordset1 = Ordset2 = Ordset3 = ordset(term())

    Returns only the elements of Ordset1 that are not also elements of Ordset2.

to_list(Ordset) -> List

    Types:

        Ordset = ordset(T)
        List = [T]

    Returns the elements of Ordset as a list.

union(OrdsetList) -> Ordset

    Types:

        OrdsetList = [ordset(T)]
        Ordset = ordset(T)

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

union(Ordset1, Ordset2) -> Ordset3

    Types:

        Ordset1 = ordset(T1)
        Ordset2 = ordset(T2)
        Ordset3 = ordset(T1 | T2)

    Returns the merged (union) set of Ordset1 and Ordset2.

SEE ALSO

gb_sets(3erl), sets(3erl)