Re: How to install an old package version?

[cdelia]

Hi!

real newbie to guix here!

> You have to make your own package for this version, that would look 
> like
> this:
>
> (define-public python-2.7.10
>  (package
>    (inherit python)
>    (version "2.7.10")
>    (source (origin
>              (inherit (package-source python-2.7))
>              (uri (string-append "https://www.python.org/ftp/python/";;
>                                  version "/Python-" version ".tar.xz"))
>              (sha256 (base32 "some-letters-and-numbers"))))))
>
> and to put it to a file from GUIX_PACKAGE_PATH.
> See (info "(guix) Package Modules") for details.

This brings me some doubts.

How does guix resolves de dependency tree in those cases? Say I need a 
previous package X version, that depends on an earlier package Y version 
that the one that is defined on the "main" guix.

Do I have to do the sema that Alex suggests so guix can resolve it? I 
guess that'll be the answer. But in that case I'll maybe find myself in 
a time consuming recursive package definition.

> Alternatively, you can use a guix git checkout on a specific commit 
> that
> still has python-2.7.10, but it's probably not what you want.

So, to avoid recursive definition of packages: Could I checkout an 
earlier guix revision, install the package and then checkout the latest 
guix version?
Would that work or it will bring other kind of dragons?

If that's the case, it could be done automatically. Does anybody try to 
do it, so we can simple specify the version of the package to install in 
"guix package" cmd?