Use tree-sitter

[catern]

Has anyone given thought to using tree-sitting in tuareg? (Or writing a new mode from scratch with tree-sitter and taking this opportunity to do some compatibility-breaking fixes on tuareg?)

[Chris00]

We have. IMHO, it probably would be a good idea. Someone will have to step in an do it though — I do not have the time for that.

[bbatsov]

Seems someone created an ocaml-ts-mode a while ago https://github.com/terrateamio/ocaml-ts-mode I see the treesitter code is like 200 lines, so perhaps we can do something similar here.

Or we can ask the author to merge his mode with Tuareg, as it seems he hasn't implemented indentation using treesitter and uses Tuareg for it. /cc @orbitz

Given the small size of our community, probably fewer major modes are better for everyone.

[monnier]

I'd welcome support for treesitter, indeed, and generally consolidating modes rather than having yet more of them (it's bad enough that we have caml-mode and tuareg-mode 😦 ).

[catern]

If any existing tuareg-mode contributors are interested in adding treesitter support, my employer would be interested in funding that work. Since we have a number of extensions to OCaml syntax which often break tuareg-mode's syntax highlighting, it would make our life easier if tuareg-mode used a tree-sitter grammar (which, since it's useful for more than just Emacs syntax highlighting, is more likely to be kept up to date). So if anyone's interested (or knows someone who might be interested), you can email me at sbaugh@janestreet.com (sorry if this comment is inappropriate here)

(We've also been considering making a new treesitter-based mode from scratch simply because it would be easier, and has the potential to go into core Emacs which might be nice. But improving tuareg-mode would probably be better)

[bbatsov]

I've started to experiment with a TreeSitter-powered OCaml mode here https://github.com/bbatsov/neocaml Let's see how far I'll be able to get. For now I prefer to work in a fresh project, just because it's much easier to play with TS this way, but if I get to a meaningful place I'd be happy to adapt the TS features for Tuareg.

My initial impressions are that getting font-lock support and structured navigation is fairly easy, but I'm guessing the indentation part will be trickier given OCaml's syntax. I'm hoping I'll be able to adapt Tuareg's SMIE approach to TS somehow.

[tmcgilchrist]

@PizieDust and I have been working on Combobulate support for OCaml in https://github.com/tmcgilchrist/combobulate/. As part of that we have some bridge code to load tree-sitter grammars into Tuareg mode, which allows us to have Combobulate running in Tuareg. What I'll end up doing is defining a minimal ocaml-ts-mode that just does the minimal font-lock work and reuses Tuareg's SMIE setup, and can be enabled in Tuareg using a defcustom flag. This is the same approach rust-mode takes.

[tmcgilchrist]

I've hacked together a good amount of treesitter functionality for Tuareg in tmcgilchrist#1 including new tree-sitter grammars for (dune and opam) and improvements to existing grammars. It might be interesting for people to try out but I'm furiously hacking on it so don't expect it to always work. In my local testing using Emacs daily it's quite stable and works as expected.