Re: Questions regarding substitutes with debug output

[Ricardo Wurmus <rekado@elephly.net>]

Olivier Dion <olivier.dion@polymtl.ca> writes:

> On Fri, 29 Apr 2022, Ricardo Wurmus <rekado@elephly.net> wrote:
>>> Even if I were to import locally defined packages, their dependencies
>>> would come from the Guix's main channel!
>>
>> What would you think about WITH-CHANNELS that would accept a list of
>> channels and evaluate any package reference in its body within an
>> inferior of those channels?
>>
>> E.g.
>>
>> (with-channels %my-channels
>>   (package
>>     (name "yay")
>>     …
>>     (inputs
>>       (list foo bar baz)) ;these are all looked up in %my-channels
>>     …
>>     (license gpl3+)))
>
> What about dependencies?  Says I have the following graph:
>
>  G <- Guix's channel
>  C <- My channel
>
>  P@V <- My package at version V from C
>  D@U <- Dependency of P at version U from G
>
> The `guix time-machine` allows me to pin the commits of G and C and thus
> pinning V and U.  Would that work the with WITH-CHANNELS ?  

Exactly the same way.  The first argument to WITH-CHANNELS would be
(cons C G) and thus P and D would be picked from the set of C and G.  C
and G can be specified with exact commits or branches, just like the
--channels option to “guix time-machine”.

We already have all the tools for WITH-CHANNELS — that’s (guix
inferior).  We just don’t have a convenient syntax to do this without a
lot of boilerplate.

-- 
Ricardo