Unifying object-oriented programming with typed functional programming

The wide practice of object-oriented programming in current software construction is evident. Despite extensive studies on typing programming objects, it is still undeniably a challenging research task to design a type system for object-oriented programming that is both effective in capturing program errors and unobtrusive to program construction. In this paper, we present a novel approach to typing objects that makes use of a recently invented notion of guarded dependent datatypes. We show that our approach can address various difficult issues (e.g., handling "self" type, typing binary methods, etc.) in a simple and natural type-theoretical manner, remedying the deficiencies in many existing approaches to typing objects.