I wish you could use Genera. If you like emacs/slime. You would see how much we lost :(
But.
Genera has been gone for over 30 years. At the time, it was certainly revolutionary. But in the computing world, where things move VERY fast, whatever made Genera amazing clearly wasn't amazing enough to replicate in full anywhere else.
I'm not even talking about other languages, trying to get that dynamic environment in modern languages, with modern tooling (which has made enormous strides over the years). But not even in the Lisp world has it resurfaced. Nobody is talking about how amazing Franz Lisp is, or LispWorks, both long running, successful Common Lisp implementations. Run by smart people, run by people "who were there".
We have Slime, with Emacs. We've had Slime forever. We've had solid Common Lisp implementations...forever! People still lament how good the Macintosh Lisp environment was (and honestly, I don't know how, or what made it more than what Slime might offer beyond nice access to the Mac toolbox).
Do you know what has changed in modern Common Lisp implementations since Genera? NOTHING! It's Common Lisp! Common Lisp is 30 years old, and a superset of whatever Lisp Genera was running. And you can't tell me that we don't have modern Genera because Flavors (Genera's object system) is so amazing and CLOS is lacking (because even if it was, it's Common Lisp -- you can FIX IT!, or simply implement Flavors because it's written in LISP!).
There are no secrets here.
Veterans speak of Genera in hushed tones. Sing songs about it. But, however good it was, it's, demonstrably, not good enough to do it again.
Meanwhile, there's been a dedicated pack of folks over at the Pharo side making Smalltalk even more Smalltalk with lots of new development tooling. These are folks that write Pharo so that they can make writing more Pharo even better. I swear, I think they're to the point that they just mount GIT as a file system now over there. I'm not a Smalltalk guy, but, boy, those folks have been riding a rocket for years.
So, it's not lost. It's abandoned. Left behind. For whatever reason. There's a difference.
Eh. That's a non-starter. The code may be closed, the concepts aren't. We've been reinventing the wheel for ages, and the Genera developer experience apparently isn't novel enough to be worthy of being reinvented.
GNU Emacs plus SLIME is a remote development environment for an external Common Lisp, using a text-editor-based environment.
Macintosh Common Lisp was an integrated GUI-based Common Lisp develop environment written in itself.
Those are two very different things.
> Flavors (Genera's object system)
CLOS and Flavors are both Genera's object systems. CLOS was actually co-developed by Symbolics. The core designers were Keene & Moon from Symbolics Inc., Kiczales & Bobrow from Xerox PARC. and DeMichiel & Gabriel from Lucid Inc.
Imagine running Common Lisp in bare metal. Like Mezzano OS does, but with your Intel malware ^U CPU firmware designed to run CL at even faster speeds.