Naughty Dog games (up to Uncharted) used to be written in a Lisp without garbage collection. The same guy then wrote the ITA flight search system. I think he may be the only productive Lisp programmer in the world.
Back in the 2000's, someone wrote a game debugging tool in Squeak Smalltalk which ran concurrently with the game (written in C++) it was debugging. It "cheated" on its garbage collection by shutting GC off. At the end of each game loop tick, it was modified so it just disposed of all objects which weren't manually marked "to keep."
That sounds like the best way to do GC in a game. Another way is to use explicit memory pools, remember to allocate from the right pool, and throw it all out at once.
General GC is really overrated I think. Automatic retain counting is nicer because it's deterministic and you never have to scan memory. Compaction can be nice but you can live without it.
I consult for a company that uses Common Lisp to design state-of-the-art network router chips. An e-commerce system that I wrote in CL powers my web site.
That depends on your definition of "written in." The transpiled Lisp code isn't at all what a human would or probably even could write. Don't forget about all those optimizations that get directly translated.
Its not unlike the 90's disasms. They compile. They work. But no human writes that kind of code that results when disassembling an optimized high level language's output.
"Someone" means a human, and that's where you are probably quite wrong.
The same point would then be that Overwatch or Assassin's Creed could be written entirely in Assembler "by someone", because a disassembler can output asm code that compiles to the exact binaries needed to reproduce it.
Yes, it can just like every other Turing complete language. Even Qbasic can do it this way. Let's get back to what a human "someone" can program in the language instead of these high level computer generated abstractions through Turing complete languages.
Waterloo Basic with all its crazy line numbers could do it entirely using PEEKs and POKEs with the logic you are clinging to. And it'll be just as unreadable as the interpreted LLVM is. And exactly as fast.
LLVM can be interpreted in Brainfuck. How far down the rabbit hole can we go before you interpret the whole thing in 1's and 0's? Crazy thought!
Try the conversion yourself and look at the results. It isn't anything like what a human could be expected to read and write. I use it often enough, and I can assure you I'd never want to be the chump who hopes to refactor it into realistic / maintainable Lisp code. What makes this useful at all is the already long-standing CLOS.
It serves its purpose. But you are over-glorifying the merits of the fact that Lisp is Turing complete like so many other languages that came after it.
Other people have already pointed out a speed penalty that I won't cover here. It works, but its not the OG... with enough time and effort, it could be. But for now, it isn't even close.
