Hartmut Goebel schreef op wo 23-02-2022 om 09:57 [+0100]:
> TL;DR: What do you think about the idea of an „extracting dowloader“?
> 
> I'm about pick up work on „extracting downloader“ and the rebar build 
> system (for erlang), see <https://issues.guix.gnu.org/51061> for a first 
> try, In the aforementioned issue some points came up regarding the basic 
> design of the patch. Thus before starting to write code, I'd like to 
> agree on a basic design.

Could the ‘extracting’ downloader be built on top of the regular
downloader?  More concretely:

(package
  (name "some-package-from-hex")
  (source
    (extract-from-hex
      (origin
        (method
          "http://some-url-pointing-to-a-tarball-wrapped-in-a-tarball")
        (sha256 (base32 <hash of the wrapper tarball>)))))
  (build-system ...))

Here, 'extract-from-hex' would turn a file-like object into a <extract-
from-hex>, which lowers to some derivation extracting the tarball from
the tarball.  (guix upstream) might need to be modified to support
<extract-from-hex>.

Also, is there some fundamental reason that hex.pm wraps tars inside
tars and only provides the wrapped tars, or could hex.pm be convinced
to also serve the underlying tars directly?

A benefit of delegating the actual downloading to url-fetch, is that
(guix scripts perform-download) would be used, so connections could be
cached.

Greetings,
Maxime.