Making mtxrun work with ConTeXt.

[Jacob MacDonald <jaccarmac@gmail.com>]

Hopefully this is a quick question, as I've found a solution for the
immediate issue and hopefully for the long term as well. I wanted to
follow up on an old thread and see if my understanding of mtxrun is
correct.

I added the whole texlive distribution to my profile, built some
documents with pdflatex, and tried to compile a template which used
ConTeXt. It failed, unable to find the context.lua script. I tracked
down the file and set my TEXMF environment variable to
$GUIX_PROFILE/share/texmf-dist. This allowed mtxrun to work, but broke
pdflatex (pdflatex.fmt not found). This seems to be because the
scripts are in texmf-dist while the format files are in texmf-var. I
found one thread on this list about a similar issue from last year,
and the incoming changes to the texlive tree. Elsewhere on the
Internet, I found the suggestion that my mtxrun file database was out
of date.

Indeed, running mtxrun --generate (after unsetting TEXMF) seems to
solve my issue, allowing me to compile both documents without tweaking
environment variables. The generator seems to dump its index into
~/.texlive2019/

Is this a necessary step to use texlive-context-base on Guix? Or can
it somehow be rolled into the build/install process? If the answer is
yes, I can try my hand at a patch.

Thanks,

Jacob.

Thread in question:
https://lists.gnu.org/archive/html/help-guix/2019-08/msg00020.html