Another way of stating this is to say that sets are “extensional” and types are “intensional,” which means that a set is defined by imposing conditions (constra

Another way of stating this is to say that sets are “extensional” and types are “intensional,” which means that a set is defined by imposing conditions (constraints) on the membership or by simply listing the objects, while a type is defined by describing its “meaning,” e.g. by specifying operations on objects.