Re: [PATCH v2 1/2] packages: Support for full Guix specification

[Olivier Dion]

On Tue, 26 Apr 2022, Ricardo Wurmus <rekado@elephly.net> wrote:
> Hi Olivier,
>
> thank for the patch!
>
>> -(define (lookup-package specification)
>> +(define (%lookup-package name+version output)
>> +  (list (match (apply lookup-inferior-packages
>> +                      (cons (current-guix) (string-split name+version #\@)))
>
> I don’t think we need the cons here.  As long as the last argument to
> APPLY is a list everything’s fine.

Oh I didn't knew that! Awesome!

>> +          ((first . rest) first)
>> +          (_ (raise (condition
>> +                     (&gwl-package-error
>> +                      (package-spec (string-append name+version 
>> output)))))))
>> +        output))
>
> I’d prefer to have this return multiple values instead of a compound
> value.

With (values ...)?  That's what (gnu packages) does I think.

>  And if it had to be a compound value for some reason I’d prefer
> to use a dedicated data type (a record value) instead of a list.

A record would be a better fit than a list yes.

>> +
>> +(define* (lookup-package specification #:optional (output "out"))
>>    (log-event 'guix (G_ "Looking up package `~a'~%") specification)
>> -  (match (lookup-inferior-packages (current-guix) specification)
>> -    ((first . rest) first)
>> -    (_ (raise (condition
>> -               (&gwl-package-error
>> -                (package-spec specification)))))))
>> +  (match (string-split specification #\:)
>> +    ((name+version sub-drv) (%lookup-package name+version sub-drv))
>> +    ((name+version) (simple-package (%lookup-package name+version 
>> output)))))
>
> I’m not sure about forcing SIMPLE-PACKAGE to be used because the return
> value might be an output.  The stuff in (guix inferior) also doesn’t
> know about outputs, so I feel that we shouldn’t attempt to include
> syntax for selecting outputs.  IIRC we’ll end up with all outputs in the
> environment, so there’s no actual effect of picking a specific output.
> I’d prefer to revisit this once (guix inferior) supports selecting
> outputs.  What do you think?

I do think it would be better to wait for (guix inferior) to support
selecting outputs.  However, I do need selection of outputs for my use
case right now!  Specificaly, I need to have debug symbols of many
packages.  The quick hack above does the work for me but I understand
that it would be preferable if (guix inferior) has support for outputs
instead.

For example, try the following:

--8<---------------cut here---------------start------------->8---
process test
  packages "coreutils" "make"
  # {
    ls $_GWL_PROFILE > "result.txt"
  }

workflow wf
  processes test
--8<---------------cut here---------------end--------------->8---

and you will see that there's no `lib/debug` directory.  So not all
outputs are in the profile.

What would you suggest I do in the meantime?  I have to publish for
december and I don't think we will see this feature very soon.  I can
keep this patch on my side for my use case, but it would be awesome if
we have a none ad-hoc solution by the time of publication :-).

Regards,
old

-- 
Olivier Dion
oldiob.dev