Re: User story: typst multiline math in pandoc markdown and pandoc AST

[John MacFarlane <fiddlosopher-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

> On Oct 20, 2023, at 12:40 AM, Guillaume Dehaene <guillaume.dehaene-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> 
> 
> Thank you for your insight.
> 
> 1. I'm not 100% satisfied with your solution since it does not work with latex environments which open math-mode (such as a align). These produce errors because of the double-opening of math-mode. It's also pretty cumbersome compared to usual md.
> 
> I see that this is how pandoc parses typst equations (I should have looked!)
>     [ Math
>         DisplayMath
>         "\\begin{aligned}\n1 + 1 & = 2 \\\\\n1 + 1 & = 2\n\\end{aligned}"
>     ]
> 
> Is that now going to be the accepted format for multiline equations?

I'm not sure I understand.  This has always been possible in pandoc (and LaTeX); we use it here because it's the way to get equivalent LaTeX math to the typst formula.


Side note:

in pandoc you can also do

$$
\begin{align}
x & = 5\\
y &= 3
\end{align}
$$

even though this isn't possible in LaTeX.  Pandoc will do the right thing the output format.  Try it.

> 2. I had overlooked the possibility of writing a filter.
> The principle of the filter would then be:
> 
> parse DisplayMath
> if there are & and/or \\ present, modify the block
> depending on writer:
> - latex, HTML: transform to align
> - everything else: transform to accepted format(??) \begin{aligned}
> 
> Is that correct? If so, I'll start hacking at it in the near future.

Yes, something like that.