SET_DIFFERENCE

Description

The SET_DIFFERENCE function removes the elements of the right set from the left set. You can also use the infix operator - to achieve the same.

Example

p is Person
COUNT(
    SET_DIFFERENCE(p.countries_with_citizenships, FORBIDDEN_COUNTRIES)
) > 0

The set of citizens a person has is shortened by a list of forbidden countries. If the person is a citizen of any remaining countries, true is returned.

Using the infix operator, the same example would look like

p is Person
COUNT(
    p.countries_with_citizenships - FORBIDDEN_COUNTRIES
) > 0