Experiments with generic visitors

Abstract
Author J. Palsberg, CBJ, J. Noble

This paper gives an overview of our work on generic visitors, and it gives a comparison between two implementations, in Java and Smalltalk. For object-oriented programming, the Visitor pattern enables the definition of a new operation on an object structure without changing the classes of the objects. The discovery of generic visitors is due to striking parallels with shape polymorphic, or polytypic programming. This illustrates the connections among the various programming styles.