Support for mhchem in LaTeX / KaTeX

[jkwchui]

I am a chemist learning Elixir, and wondering if / where the LaTeX configuration is exposed. There are LaTeX packages (for both KaTeX and mathJax) that greatly facilitates chemical typesetting, but I am unable to find documentation that describes whether it could be injected.

[josevalim]

Hi @jkwchui!

Currently there is no such feature but we may be able to make this configurable. Can you tell us which package are you planning to use?

[jkwchui]

The `mhchem` package (https://mhchem.github.io/MathJax-mhchem/) is what is commonly used, and is available for both MathJax and KaTeX. Between these two, MathJax is heavier but more configurable. That said, this is an esoteric use-case. Coming from python / Jupyter / JS frameworks, I was stunned at how coherent Elixir and its ecology had been. (Obrigado Jose!) I allocated half-day to troubleshoot setting up Livebook, but it *actually* Just Worked (??!!) and the Fly.io deploy was *really* one-click (??!!). That’s so awesome, and would be a shame to see it cluttered up with low usage configuration options.

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On 13 Jun 2022 at 4:21:31 PM, José Valim ***@***.***> wrote: Hi @jkwchui <https://github.com/jkwchui>! Currently there is no such feature but we may be able to make this configurable. Can you tell us which package are you planning to use? — Reply to this email directly, view it on GitHub <#1224 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAF5L6YUWZSVYUZR2XGK5N3VO3VQXANCNFSM5YTI4ZZA> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[josevalim]

I wonder if we can use a custom macro in KaTeX to implement MathJax \require{mhchem}. The macros mechanism is defined here: https://katex.org/docs/options.html

This would support custom extensions in the future and align with usage elsewhere. Although perhaps it is worth waiting a little bit until more use cases arrive!

[jonatanklosko]

mhchem is one of the few extensions in the katex package, and it adds only 30kb to the bundle, so I would be fine just enabling it.

GitHub actually supports it out of the box:

$\ce{Hg^2+ -&gt;[I-] HgI2 -&gt;[I-] [Hg^{II}I4]^2-}$