[c256]

There have been several recreations of Emacs in Common Lisp over the years, including Hemlock, CEDAR, and Climacs. They never catch on, because they’re not compatible enough with the existing base of emacs lisp software. This also applies to Scheme, although it did get closer to compatibility once or twice. This is also closely tied to why emacs hasn’t been made much more parallelized - fundamentally, the design of emacs is too close to “a giant ball of global state”, mirroring an early Lisp Machine. It’s a high hill to design around, and it will violate basic assumptions made by most medium-plus interesting elisp code. Do not let this dissuade you from trying! It would be a great if difficult accomplishment!

[vindarel]

Lem is actually useful though! And not a recreation of Emacs in CL, it's its own thing, unlike CEDAR (which wasn't completed).