Should I include font as a dependency to OpTex?

[Ashvith10]

I am trying to fix the current OpTex package on Guix by replacing luatex with luahbtex - and it seems to be working now (seems to build documents just fine when paired with texlive-scheme-minimal).

I was wondering if I should also include texlive-lm-math as a dependency? Or do I remove texlive-lm and make it optional/flexible for the users to pick their font of choice (that is, they will have to add texlive-lm and texlive-lm-math to the Guix manifest)?

[olsak]

The \fontfam[lm] commend which loads Unicode Latin Modern font family is presented in many documentation as a minimal starting point for creating a document. See page 5 of OpTeX doc for example (hello world example). Of course, the following example at the same page shows \fontfam[termes], i.e. user should select a font family. But it would be good if we were sure that at least one font family is installed. And Latin Modern is good candidate for this because it has similar shape as Computer Modern from original TeX. The page 5 of OpTeX doc also writes "You can try to process optex op-demo". This document uses \fontfam[lm], i.e. it loads Latin Modern fonts.

If a font isn't found then OpTeX prints warning only (no error) and reverts to non Unicode fonts loaded internally in the format. The diacritical marks and many special characters doesn't work well in this case. These fonts are intended only for testing of developed macros and behaves similarly like fonts in classical Plain TeX by D. Knuth.

If the \fontfam[lm] is used but latinmodern-math (i.e. texlive-lm-math) isn't installed then OpTeX prints warning:

WARNING l.x: Math font "[latinmodern-math]" not found, skipped....

and OpTeX reverts to classical non-Unicode math setting (like in Plain TeX). Many features don't work in this case, see
optex-math, the right margin: the word Unicode means that this works only in Unicode math. Moreover, about 90 % features provided by the package math don't work too.

These aspects are not documented in detail because we assume that Unicode fonts for text and math are available in the TeX distribution and users need not t solve these problems.