Re: Will 2021 be the year of build systems on gexps?

[Ludovic Courtès]

Hello!

Ludovic Courtès <ludo@gnu.org> skribis:

> Over the last few days I’ve been head-down working on
> ‘wip-build-systems-gexp’, the mythical branch that brings gexps to build
> systems and packages, so we can say goodbye to
> ‘build-expression->derivation’.  And… it’s quite a ride!

The current tip of ‘wip-build-systems-gexp’ Just Works; it’s being built,
it can build ‘guix’ and cross-build things like ‘sed’:

  
https://data.guix-patches.cbaines.net/repository/2/branch/wip-build-systems-gexp

  https://ci.guix.gnu.org/jobset/wip-build-systems-gexp (though Cuirass
  currently has unrelated problems)

In terms of performance, there’s still a ~10% slowdown when computing
derivations compared to the ‘core-updates’ revision the branch is based
on.

Here’s what I’d like to do in the coming days, if that doesn’t interfere
with what others have in mind for the upcoming release:

  • Monitor build failures due to typos/thinkos made while adjusting
    build systems;

  • Merge on ‘core-updates’.

Then there are optimizations to work on, but that can take a bit longer.
In particular, in ‘gexp->derivation’, allow file-like objects to be
specified as environment variable values.  In turn, use that so that,
say, ‘gnu-build-system’ has a single builder for all its packages and
just calls ‘getenv’ to get the value of its various parameters, similar
to what (guix git-download) does.

That said, if people think it’s too late in the cycle, we could just as
well keep it for the next cycle.

Thoughts?

Thanks,
Ludo’.