[tlbuild] LuaMetaTeX for TeX Live

[Mojca Miklavec]

Dear Karl,

On Sat, 17 Sept 2022 at 00:25, Karl Berry wrote:
>
>     officially live under
>         https://github.com/contextgarden/context/tree/main/source/luametatex
>
> Excellent news.
>
>     The build is done using CMake, so I'm not sure about the best way to
>     integrate it into the current autotools-based toolchain.
>
> As far as I can imagine, it is impossible. (Also, FWIW, I have no
> interest in spending any time thinking about cmake in any way, so if
> it's going to happen, someone else will have to work on it.)

It seems that some CMake-based projects simply "manually" call
"configure" on some of their dependencies.

The luametatex sources are really straightforward to compile, with no
dependencies, just "cmake <path-to-source>" when configuring and
"cmake --build <path-to-source>" when building. Maybe those two
commands could be called from autotools.

I'll try to look into it, but I would be enormously grateful to get a
bit of help.

>     so the binaries for most relevant platforms are already available (and
>     could be made available at particular commits/branches to match what
>
> It seems reasonably possible to import your lmtx binaries into TL

Awesome, thank you. It always helps to know that a backup plan is viable.

> A lot more possible than doing anything with cmake in
> the build tree, at least.  The missing platforms aren't a problem as far
> as I'm concerned.
>
> To make the formats, do users then run "context --generate", as with
> mkiv?  (At least as far as I know that's what is done with luatex/mkiv.)

Yes. (In reality this might not even be strictly needed, ConTeXt
automatically detects the need to generate a new format and does it on
the fly when compiling the first document, but it definitely doesn't
hurt to run "context --generate" just in case.)

> That is, nothing more needs to happen at TL installation time? That
> would be good.

No.

The only thing that's needed is of course a package for the new engine
and appropriate dependencies. Maybe some minor tweaking when importing
ConTeXt sources into the tree.

> More generally, though: I was under the impression that lmtx is Hans's
> playground and as such is constantly changing.

The LuaMetaTeX engine has been in development for nearly 4 years
already and has by now been adopted by the great majority of ConTeXt
users already.

Of course the initial development was a fast moving target (it had to
be), but it has become mostly feature complete by now (of course there
will be bugs that will need fixing) and can safely replace LuaTeX, at
least for ConTeXt users (the same cannot be said in general since the
engine also removed quite a bit of functionality from LuaTeX).

> So what is the gain in having a particular build frozen into a TL image?

One snapshot per year sounds perfectly fine for anyone who doesn't
need "the brand new feature from yesterday".
I would say that the question is pretty comparable to "what's the
point of including one particular version of LuaTeX into TL" that one
would have asked some years ago when LuaTeX was not yet "frozen".

Mojca