parser VS elisp-tree-sitter

I have mixed feelings on Rust's syntax, especially around generics, lifetimes, and the `modifier -> keyword` syntax (i.e. `async fn` or `pub fn`). For Inko, I wanted something that's easy to parse by hand, and no context specific parsing (e.g. `QUOTE -> something` being the start of a lifetime in one place, but a char literal in another place).

Another motivator for that is that years ago I worked on Rubinius for a while (an implementation of Ruby), and helped out with a parser for Ruby (https://github.com/whitequark/parser). The Ruby developers really liked changing their already impossible syntax in even more impossible ways on a regular basis, making it a real challenge to provide syntax related tools that support multiple Ruby versions. I wanted to avoid making the same mistake with Inko, hence I'm actively trying to keep the syntax as simple as is reasonable.

As for the specific examples:

- `fn async` means your parser only needs to look for `A | B | fn` in a certain scope, instead of `A | B | fn | async fn`. This cuts down the amount of repetition in the parser. An example is found at https://github.com/inko-lang/inko/blob/8f5ad1e56756fe00325a3..., which parses the body of a class definition.

- Skipping parentheses is directly lifted from Ruby, because I really like it. Older versions took this further by also letting you write `function arg1 arg2`, but I got rid of that to make parsing easier. It's especially nice so you can do things like `if foo.bar.baz? { ... }` instead of `if foo().bar().baz?()`, though I suspect opinions will differ on this :)

- Until recently we did in fact use `::` as a namespace separator, but I changed that to `.` to keep things consistent with the call syntax, and because it removes the need for remembering "Oh for namespaces I need to use ::, but for calls .".

- `[T]` for generics is because most editors automatically insert a closing `]` if you type `[`, but not when you type `<`. If they do, then trying to write `10<20` is annoying because you'd end up with `10<>20`. I also just like the way it looks more. The usual ambiguity issues surrounding `<>` (e.g. what leads to `foo::()` in Rust) doesn't apply to Inko, because we don't allow generics in expressions (i.e. `Array[Int].with_capacity(42)` isn't valid syntax) in the first place.

So there was this really awesome gem called parser written by someone not on the core team that gives you a super clean understanding of the Ruby code. Not only does it not care if the parentheses are there or not, but there's a really well structured and precise mapping of where the information comes from and it is completely semantic. So if you've got parentheses or not, it's not gonna make any difference in the structure of your abstract syntax tree, but you can actually ask where are the locations. That is taken care of, but the understanding of the code, what's going on in the code is completely independent of if you wrote those parentheses or not.

Working with those things, possibly with the help of reading books, tends to be how it's learned I'd say. I'm not the one you asked, but I personally worked with Ruby for 10 years, worked on a system to improve coverage reports, which relied on rewriting ruby code. Doing so was done using the Parser gem, which is a ruby parser that has a different abstract syntax tree (https://github.com/whitequark/parser). I'm also interested in programming languages development, so I try to read on this / develop my own language in my free time.

Changes like this have been going on for years. I remember that back when I was still helping out with https://github.com/whitequark/parser, the author on a regular basis had to deal with Ruby making yet more non-trivial syntax changes. IIRC they eventually burned out on the project because of that, but my memory is a bit fuzzy.

This is more a function of Ruby than of tree-sitter. The tree-sitter grammars for other languages are hopefully less inscrutable. For Ruby, we basically just ported whitequark's parser [1] over to tree-sitter's grammar DSL and scanner API.

[1] https://github.com/whitequark/parser

Look at the original integration project https://github.com/emacs-tree-sitter/elisp-tree-sitter, before it was done inside Emacs 29+.

When tree-sitter is available you may extend expand-region with this one one https://github.com/emacs-tree-sitter/elisp-tree-sitter/issues/20 Works very nice for me. But simple matching pairs should be handled well by expand-region alone

That said, if you want a more complete experience with tree-sitter right now, there’s a 3rd party implementation with support for a lot more languages, and also automatically downloads all supported grammars. It’s available here: https://github.com/emacs-tree-sitter/elisp-tree-sitter

Just like there are multiple LSP implementations for emacs (lsp-mode, eglot, lsp-bridge), there are multiple tree-sitter implementations. The one recently included in emacs was never a standalone package, I believe (correct me if that’s wrong), but was created with the purpose of being included in emacs. You will need melpa to download the linked elisp-tree-sitter package (https://github.com/emacs-tree-sitter/elisp-tree-sitter), but not the built in one.

How am I going to even use the built-in one? I was using elisp-tree-sitter. I know I have to add grammar for different languages, but how? I have been searching for a while and still have no clue.

from github README.rst "Emacs package that provides a standardized framework for manipulating and navigating your source code using tree sitter's concrete syntax tree " -> https://github.com/mickeynp/combobulate

https://www.spacemacs.org/ with https://github.com/emacs-tree-sitter/elisp-tree-sitter then write a iterator/loop query for language(s) editing per https://tree-sitter.github.io/tree-sitter/syntax-highlightin...

tad less installation heavy (sorta) but also makes use of tree-sitter syntax queries : https://www.lunarvim.org (neovim with treesitter syntax)

blockman usage examples: https://www.youtube.com/channel/UC5539gDeAdWqeXcczWuhnBA

Alternative examples / takes (per user interface):

### embedding a block of source code in a document:

  ** carrotsearch.gethub.io/apidocs/code-blocks

However, if you want to use tree-sitter today, there is the tree-sitter package which enables tree-sitter syntax highlighting in a number of popular major modes. I’ve been using it for about six months now in all major modes it supports.

Tree Sitter and lsp-mode might be of help. Looks like both take a bit of work to get going. I have personally not used them, so try out which suits you and let us know how it went.

You can use tree-sitter already if you have dynamic module support: https://github.com/emacs-tree-sitter/elisp-tree-sitter