Pandoc Typst property thoughts

[wlupton]

(The first part of this background discussion. The proposal is marked PROPOSAL below.)

A while back I created #8988. It considered this example markdown:

::: note
This is a note.
:::

and one idea was that this could become Typst code like this:

#note[This is a note.]

This will only work if a Typst note function has been defined, so @jgm suggested that only special classes, e.g., starting typst-, might be passed through to Typst. A lua filter might convert the note class to typst-foo-note (where foo is a prefix that acts as a namespace) and the emitted Typst code might be this:

#foo-note[This is a note.]

I have been doing something like this for a while, using a custom writer. It will output this:

#bbf-note[
This is a note.
]

If there are multiple classes the calls are nested, e.g., this:

::: {.note .gray}
Another note.
:::

outputs this:

#bbf-gray[
#bbf-note[
Another note.
]]

PROPOSAL

I'd prefer to use the built-in Typst writer, so I took a look at Pandoc Typst properties. They don't seem to designed to call styling functions such as my bbf-note but I wonder whether they could be extended to do so.

I believe that they currently only use key=value attributes, and not classes, so potentially a typst:func class could specify a function to be used in place of the element that would otherwise be used (nothing for span, block for div, table for table etc.). This:

::: {typst:breakable=false}
div
:::

currently outputs this:

#block(breakable: false)[
div

]

and this:

::: {typst:bbf-note typst:breakable=false}
div
:::

would output this:

#bbf-note(breakable: false)[
div

]

Does this sound like a reasonable idea? If so, I'd be happy to make a more complete proposal.