I would describe an effect system as the part of a type system which describes actions and side effects rather than values. Under this definition, effects are r

I would describe an effect system as the part of a type system which describes actions and side effects rather than values. Under this definition, effects are radically different from types in the sense that apples are radically different from fruit. This requires a somewhat broad notion of what types are in the first place. I think most people have a mental model of types that describes data types like int or string, but anyone familiar with Java knows what effects are because Java has the “throws” keyword, which is an effect. If your method in Java throws IOException, the method must be marked “throws IOException” or it is a type error. So I think our definition of “type” should be broad enough to include effect systems.