Problem Statement

Multiple inheritance allows to specify that one class is a subclass of several other classes. Some languages allow multiple inheritance for arbitrary classes,   others restrict it to interfaces,   some don't allow it at all.

Write two classes (or interfaces) Camera and MobilePhone,   then write a class CameraPhone which is both a Camera and a MobilePhone. There is no need to implement any functions for those classes.

Let's start with the solution:

(defprotocol Camera)

(defprotocol MobilePhone)

(deftype CameraPhone []
  Camera
  MobilePhone)