FRED ("Fred Resembles Emacs, Deliberately") is the  MCL editor. It is functionally equivalent to  Emacs, though built on (and extended by) Common Lisp, rather than Emacs Lisp.

The original FRED is based on MCL's CLIM. OpenMCL's FRED should probably be built on top of the Cocoa bindings, or perhaps built using some kind of cross-platform (OpenGL?) widget set.