Re: Different comment syntaxes in within the same buffer?

On Fri, Apr 10 2026, Stéphane Marks wrote:

> On Fri, Apr 10, 2026 at 12:02 PM Stefan Monnier via Users list for the GNU
> Emacs text editor <[email protected]> wrote:
>
>> > I would like to ask the Lispers here whether there is a good solution
>> > for having different comment syntaxes in the same buffer depending on
>> > the point's position. For more context, a lot of web templating
>> > languages (e.g., Svelte, Astro) have multiple syntaxes in the same file.
>> > For example, Astro filles have a "frontmatter" section where JavaScript
>> > can go, then after the frontmatter section goes CSS and/or HTML.
>>
>> Presumably you'd like Emacs to handle correctly not just the comments
>> but also the highlighting of the rest, as well as the indentation,
>> etc...
>>
>> IOW, you need a major mode that understands that the file is split into
>> several sub parts each one using a different major mode.
>> AKA "multi major modes".
>>
>> There are various packages that provide solutions for that, such as
>> `mmm-mode` and `polymode`.
>>
>> The built-in `mhtml-mode` also does it for the specific case of HTML
>> files including CSS and Javascript elements.
>>
>
> We've done this to a large degree in the new `markdown-ts-mode`.  All
> fenced code blocks are fontified in their mode using either treesit or
> conventional font-lock and special handling for embedded markdown code
> blocks and also modes like php-ts-mode which itself hosts many
> subordinate treesit parsers.  We made it so that commands run in the
> context of each code-block's mode with some hacking so
> `indent-for-tab-command` `newline` etc., work.  It's not Van Gogh but it
> mostly works, so a da Vinci.
>
> The code has not yet been installed and is under discussion.  I can send it
> to you or you can look on the list if you want to see how it works.

Oh, that sounds interesting. If possible, could you share the most
recent version of the code you have? Thank you.

-- 
Kind regards,
Kristoffer