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.

       This  module  provides  exactly  the  same interface as the module sets 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

       new() -> []

              Returns a new empty ordered set.

       is_set(Ordset) -> boolean()

              Types:

                 Ordset = term()

              Returns true if Ordset is an ordered set of elements, otherwise false.

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

              Types:

                 Ordset = ordset(term())

              Returns the number of elements in Ordset.

       to_list(Ordset) -> List

              Types:

                 Ordset = ordset(T)
                 List = [T]

              Returns the elements of Ordset as a list.

       from_list(List) -> Ordset

              Types:

                 List = [T]
                 Ordset = ordset(T)

              Returns an ordered set of the elements in List.

       is_element(Element, Ordset) -> boolean()

              Types:

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

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

       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.

       union(Ordset1, Ordset2) -> Ordset3

              Types:

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

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

       union(OrdsetList) -> Ordset

              Types:

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

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

       intersection(Ordset1, Ordset2) -> Ordset3

              Types:

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

              Returns the intersection of Ordset1 and Ordset2.

       intersection(OrdsetList) -> Ordset

              Types:

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

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

       is_disjoint(Ordset1, Ordset2) -> boolean()

              Types:

                 Ordset1 = Ordset2 = ordset(term())

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

       subtract(Ordset1, Ordset2) -> Ordset3

              Types:

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

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

       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.

       fold(Function, Acc0, Ordset) -> Acc1

              Types:

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

              Fold Function over every element  in  Ordset  returning  the  final  value  of  the
              accumulator.

       filter(Pred, Ordset1) -> Ordset2

              Types:

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

              Filter elements in Ordset1 with boolean function Pred.

SEE ALSO

       gb_sets(3erl), sets(3erl)