Lecture Notes on Polymorphism

In this lecture we will start the transition from C0 to C. In some ways, the lecture is therefore about knowledge rather than principles. The underlying issue that we are trying to solve in this lecture is nevertheless a deep one: how can a language support generic implementations of data structures that accomodate data elements of different types. The name polymorphism derives from the fact that data take on different forms for different uses of the same data structure. A simple example is the data structure of stacks. In our C0 implementation, the definition of the stack interface used an unspecified type elem of elements.