On understanding data abstraction, revisited
William R. Cook · ACM SIGPLAN Notices · 2009
In 1985 Luca Cardelli and Peter Wegner, my advisor, published an ACM Computing Surveys paper called "On understanding types, data abstraction, and polymorphism". Their work kicked off a flood of research on semantics and type theory for object-oriented programming, which continues to this day. Despite 25 years of research, there is still widespread confusion about the two forms of data abstraction, abstract data types and objects . This essay attempts to explain the differences and also why the differences matter.