Math support (a.k.a. tex_math_dollars)

[Omikhleia]

We'd need:

• Support for Pandoc's tex_math_dollars extension in Lunamark (= Support tex_math_dollars extension jgm/lunamark#50) to extract the formula and invoke the writer.
• The path then for SILE has to be clarified
  • Either we assume its TeX-like math is kind of OK, though with restrictions (at this time of writing) on the supported syntax subset...
  • Or we go to the mathml route (which at the time of writing again, seems a bit better in SILE), but that would mean converting the (La)TeX formula to MathML. We are not going, certainly, to reinvent the wheel here¹, so likely use something existing, e.g. TEMML, although it implies a dependency on NodeJS and forking an external process... And MathML in SILE also has some restrictions (at the time of writing again, such as MathML msqrt not supported sile-typesetter/sile#1604, so I am unsure it's worth the effort going that route.
  • However, SILE math is not even an inputter, though I've a few doubts regarding the actual implementation, esp. with AST dumping and round-tripping... (Should we include an outputter that would just write out the output from inputter.markdown.parse(…)? #15)

Footnotes

1. The Lua ecosystem is so non-existent that the very choice of Lua for SILE could be questioned. And IMHO, Rust is not even better -- said with a grain of salt, to those in the SILE community who might argue otherwise, heh! 😸 ↩

[Omikhleia]

Blocker: As of 0.14.4, packages markdown and pandocast can no longer be used together in a single document such as the demo/showcase document if they both load the math package... It will hit sile-typesetter/sile#1607, so this will have to wait for resolution...

Other than that, going the "TeX-like math" route seems satisfying enough:

TeX-like math between `$` ("inline mode") or `$$` ("display mode") decently works
Note that $20,000 and $30,000 don't parse as math, while $e^{i\pi}=-1$ does.
There is an important constraint, though: you have to restrict yourself to the syntax subset supported
by SILE. This being said, some nice fomulas may be achieved:

::: {custom-style=center}
$$\pi=\sum_{k=0}^\infty\frac{1}{16^k}(\frac{4}{8k+1}-\frac{2}{8k+4}-\frac{1}{8k+5}-\frac{1}{8k+6})$$
:::

At the time of writing, obtained via the Pandoc AST route -- My quick'n dirty attempt on the Lunamark-native route currently breaks severely on the "note that..." test case. But I spent more time today debugging the blocker issue, and another weird one (worked-around) than seriously trying to implement the pattern right :(

[alerque]

Given that it has its own unique language, can we refactor the math language a bit to be an inputter?

[Omikhleia]

#23 has the experimental code for both inline and display math, supported both with the markdown and pandocast packages.

Looks nice: