@FILES
  {"ord-set"; "The ORD_SET signature";}
@SIGNATURE ORD_SET "ord-set" {
  @STRUCTURE Key ORD_KEY
  @TYPES 
    @TYPE item
    @TYPE set
  @VALS 
    exists
    find
    foldl
    singleton
    filter
    foldr
    equal
    difference
    map
    listItems
    add'
    app
    numItems
    isSubset
    delete
    addList
    intersection
    compare
    member
    union
    add
    isEmpty
    empty
}
@SIGNATURE ORD_KEY
@STRUCTURE IntListSet "ord-set" ORD_SET
@STRUCTURE IntBinarySet "ord-set" ORD_SET
