Re: Recent change in 'guix package --search-paths' behavior?

[ludo@gnu.org (Ludovic Courtès)]

Hi Chris,

Chris Marusich <cmmarusich@gmail.com> skribis:

> ludo@gnu.org (Ludovic Courtès) writes:
>
>> Chris Marusich <cmmarusich@gmail.com> skribis:
>>
>>> Hi,
>>>
>>> The manual says ((guix) Invoking guix package):
>>>
>>>      This option can also be used to compute the _combined_ search paths
>>>      of several profiles.  Consider this example:
>>>
>>>           $ guix package -p foo -i guile
>>>           $ guix package -p bar -i guile-json
>>>           $ guix package -p foo -p bar --search-paths
>>>
>>>      The last command above reports about the ‘GUILE_LOAD_PATH’
>>>      variable, even though, taken individually, neither ‘foo’ nor ‘bar’
>>>      would lead to that recommendation.
>>
>> [...]
>>
>>> Is the documentation wrong, or is this a regression?
>>
>> Try with “guile2.2-json” instead of “guile-json”.
>>
>> Ludo’.
>
> As usual, you're right!  :-)  That worked:

[...]

> Why does 'guix' resolve to guile@2.2.2, but 'guile-json' resolves to
> guile-json@0.6.0?

It’s because we’re not done with the transition:

  https://lists.gnu.org/archive/html/guix-devel/2017-03/msg00436.html

The idea is to incrementally rename all “guile2.2-foo” packages to
“guile-foo”, and, when needed, keep an extra “guile2.0-foo”.  For
guile-json this hasn’t been done yet, but now’s probably a good time to
do it.

> Is it because, as mentioned in the comments in procedure
> 'find-newest-available-packages' in gnu/packages.scm, "the preferred
> package is whichever one was found last by 'fold-packages'"?
>
> I've attached a patch for the documentation which might help clarify
> this for anyone who has the same question in the future.  What do you
> think?  Too much detail for an edge case, or a useful footnote?

I would rather not add more text to it because the example will become
valid again soonish, and the extra text might muddy waters.

WDYT?

Thanks,
Ludo’.