What POOP frameworks exist for Lisp and Scheme

Question

What nice POOP (Prototype-based Object-oriented Programming) Frameworks exist in Lisp and Scheme?

I know one: Sheeple

But are there any others?

Answer 1

There should be quite a few.

ObjectLisp is one. It was used on the LMI Lisp Machines and for the early Macintosh Common Lisp starting in the mid 80s.

Basically every 'Frame system' without classes can support Prototype-based Object-oriented Programming. There should something like twenty systems that should do it.

Answer 2

Prometheus is Self-like prototype system for Scheme (and Racket).