Booleans

From dis-Emi-A

A Boolean will be consistent with being treated as a Set type (though it will actually still be a special type itself).

That is, Boolean has two values:

1. False, an empty set
2. True, a set of one void element

This allows the standard operators to have the same meaning for Booleans and Set:

1. Or / Union
2. And / Intersect