[lifthrasiir]

A compositional type is just a consequence of having a good type system. It means that you can slice your requirements into multiple independent types because they are individually describable in the type system. The converse is not true, which is why C++ also seems to have a compositional type. (C++ doesn't really have a true compositional type; C++ templates have no such guarantees, and thus even harder to use than true compositional types.)