OK? It's feature in development. Eventually emacs 29 with tree sitter will be part of distro packaging, and it will just be an "apt install emacs" away.
Once Emacs 29 releases, your distro will package Emacs compiled with tree-sitter.
> you also need to have a language binding in a shared library in a known location
Emacs already ships with command that clones grammar repo, compiles, and installs the shared library to that known location - this was explained in the article. The only manual thing you need to do is to associate a language with a git repo in your configuration.
> And once you have that, you actually need someone to write a major mode that utilizes it at all.
Emacs developers have been also been working on covering major languages to provide tree-sitter based major modes. I count 23 major modes already being maintained as part of Emacs that will be shipped soon as part of 29.1, not to mention there are a lot more in Melpa (centralised community package repository).
In any case, whole thing with the tree-sitter is that it really makes writing major modes easy. It's all declarative now, including indentation rules that had traditionally been tricky to get right.
Even that setup step will be unnecessary in emacs 30, when all this stuff will be shipped by default.
> Neither tree-sitter nor Emacs come installed with language grammars
> ...it’ll only work if you don’t have an exceptional setup (so it won’t work well unless you have GCC and run some flavor of Linux.)
> Determining if a grammar is available is not intuitive nor obvious unless you use elisp
> Note that, just because you have installed a grammar, does not mean Emacs supports it. Someone still has to write the – admittedly, way easier – syntax and indentation logic and all that good stuff.
> Annoyingly, there’s no easy way to see if you’re using the normal or the TS-powered major mode
> If you use Customize, then you don’t have to do anything, but if you normally use setq, you’ll have to use customize-set-variable instead to ensure the setter is called properly.
> That sounds like a great idea until you realize that it is not possible to make one-size-fits all commands that do this. Believe me: I’ve tried.