snek is a simple data structure for working with vertices and edges. More importantly it is a programming pattern for applying changes to the structure. It is specifically written to be useful for a broad range of ways in which I usually write generative algorithms for creating art.
This text describes what the author has been doing in some more detail. Specifically it describes an experimental data structure and—more importantly—a programming system or pattern.
If you like lisp you'll find interesting this good article: