> I'm reminded of when an old C hand tells me that Rust will never replace C because it's too complex, brittle, and frustrating for the kinds of applications C programmers use C for. I always tell them: Rust isn't aimed at you -- it's aimed at your replacement.
I don't think this is a fair comparison. Emacs is a specific piece of software where implementation details are part of the offering. I don't care if parts of the Linux kernel get rewritten in Rust, I have never (extensively) looked at its code. I'll like it as much.
Being able to effortlessly examine and change other people's code is a big thing for me in Emacs. Many big Emacs users make money programming in Lisps too, it's not just some vague preference they're not willing to act on.
To implement a real mode, you WILL have to call elisp code all the time. Emacs does almost nothing asynchronously. Every tiny thing in Emacs triggers a lot of elisp that assumes sequential execution. You cannot do all the hard work in an isolated context and call Emacs once you're done. Most of Emacs performance issues have to do with latency, not long running computations. With libgccjit, native-comp Elisp is consistently 4-5 times faster (yes, really), but the actual perceived improvement is much less. Can hardly tell a difference. Emacs still hangs at all the same stuff and there's no easy fix. You'd have to completely change how Emacs works at which point it may as well be something different. I don't see how this kind of a thing can incrementally take over.
If you want to make my life better find me a way to fix long lines or get rid of GC pauses without breaking everything.