Re: [PATCH] feat: add markdown-ts-mode

[Eli Zaretskii <eliz@gnu.org>]

> From: Rahul Martim Juliato <rahuljuliato@gmail.com>
> Date: Sat, 20 Apr 2024 00:23:45 -0300
> 
> I've been using Emacs without any extra packages as an educational
> experiment after years of package hording.
> 
> 
> One of the few things I've been missing is a way of displaying some sort
> of syntax highlight for markdown documents.
> 
> 
> It feels a bit frustrating opening a README.md file with a single face
> color, since Emacs from the box can handle so much.  I am sure others
> might have shared this feeling before.
> 
> 
> This patch is a modified version of a package I've recently published on
> MELPA, screenshots are available here:
> https://github.com/LionyxML/markdown-ts-mode
> 
> 
> It is a very basic mode that provides syntax highlight and imenu support
> using treesitter grammar from
> https://github.com/tree-sitter-grammars/tree-sitter-markdown
> 
> 
> The idea here is to provide minimal support to Emacs and continue
> building up features in the future.
> 
> 
> It is the first time I contribute to Emacs devel, so please let me know
> if I did something wrong or anything is not at the expected standards.

Thanks, please see a couple of comments below.  I've CC'ed Yuan as
well, in case he has comments.

> >From 364f61b03d601d2cb3aeb1687da2d1b2a232474c Mon Sep 17 00:00:00 2001
> From: Rahul Martim Juliato <rahul.juliato@gmail.com>
> Date: Fri, 19 Apr 2024 23:21:20 -0300
> 
> ---
>  etc/NEWS                           |   5 ++
>  lisp/progmodes/markdown-ts-mode.el | 106 +++++++++++++++++++++++++++++
>  2 files changed, 111 insertions(+)
>  create mode 100644 lisp/progmodes/markdown-ts-mode.el

Please accompany the patches with a ChangeLog-style commit log
message; see CONTRIBUTE for the details.  In this case, you'd need a
very minimal one, something like:

  * lisp/progmodes/markdown-ts-mode.el: New file.
  * etc/NEWS: Announce the new mode.

> +---
> +*** New major mode 'markdown-ts-mode'.
> +A major mode based on the tree-sitter library for editing Markdown files.

How about mentioning this in the user manual as well?  It doesn't have
to be anything more than just the name of the mode.

> diff --git a/lisp/progmodes/markdown-ts-mode.el b/lisp/progmodes/markdown-ts-mode.el

Should this mode live in lisp/textmodes/ instead?  Markdown is AFAIU a
mode for text with markup, it isn't a programming language.

> +(defun markdown-ts-setup ()
> +  "Setup treesit for `markdown-ts-mode'."
> +  (setq-local treesit-font-lock-settings markdown-ts--treesit-settings)
> +  (treesit-major-mode-setup))
> +
> +;;;###autoload
> +(define-derived-mode markdown-ts-mode fundamental-mode "markdown[ts]"
> +  "Major mode for editing Markdown using tree-sitter grammar."
> +  (setq-local font-lock-defaults nil
> +	      treesit-font-lock-feature-list '((delimiter)
> +					       (paragraph)))

I wonder whether this mode should inherit from Text mode instead, and
consequently have some text-related commands, perhaps aided by the
tree-sitter grammar?  WDYT?  We could, of course, add commands later,
but the decision to have Text mode as the parent of this one should be
made now.