Re: proposal: (define (find-guix-packages list-of-names) ... )

[Florian Paul Schmidt]

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Hi, and thanks for your reply..

On 11/15/2015 09:35 PM, Ludovic Courtès wrote:

> I think ‘specification->package’ from (gnu packages) is the
> procedure you want.  Like this:
> 
> (map specification->package '("guile-2" "gnupg-2.0" "coreutils"))
> 
> It emits a warning in case the specification is ambiguous.
> 
> Maybe we could/should use it in the example GuixSD configurations,
> and at least document it somewhere.
> 
> WDYT?

Sounds like a plan. Though in this use-case I think I'd prefer an
error over a warning. For the simple reason that during system
reconfigure a warning might be missed easily. Especially after a guix
pull where suddenly a package spec might become ambiguous where it
wasn't before and a different package gets chosen.

OTOH, maybe that's overdoing it and even with the error instead of a
warning there are still some failure modes somewhat similar to this:
E.g. Package foo disappears while a quite different package foo
appears (possibly in a different module). Quite unlikely but possible.


Regards,
Flo

P.S.: Note though that there are modes like this also for the now
common practice of using use-modules in a non-local way at the top of
the config file but they are more contrived (and depend on having just
the right use-modules calls and packages in the packages list).

I'm new to guile (and scheme and guix ;), but maybe there's a way to
use use-modules in a more local fashion. Together with the guarantee
that the module/package combination is unique (not including version
changes which are to be expected during a reconfigure after a guix
pull) it would be possible to avoid those kind of surprises if needed.


- -- 
https://fps.io
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