> For example, why do you suppose that inheritance via composition makes it not an ISA relationship? I don't. My other message [1] clearly states: class A

> For example, why do you suppose that inheritance via composition makes it not an ISA relationship? I don't. My other message [1] clearly states: class A(b: B) : B by b // IS_A via composition My point is that inheritance can be achieved in many different ways, composition being one of them. Inheritance is an architecture concept, composition is a mechanism which can be used to implement inheritance. They are complementary. [1] https://news.ycombinator.com/item?id=16050458 https://news.ycombinator.com/item?id=16050458