Common Lisp the Language
2nd Edition

PREFACE:
Generators and gatherers are yet another
approach
closely related to series
to providing iteration in a functional style.
The remainder of this chapter consists of a description by Crispin Perdue and Richard C. Waters of their work on an existing implementation of generators and gatherers. I have edited the chapter only very lightly to conform to the overall style of this book. Please see the Preface to this book for more information about the genesis of the generators/gatherers approach and its relationship to the work of X3J13.
-Guy L. Steele Jr.