Re: Replacing Bower with "guix environment"

[ludo@gnu.org (Ludovic Courtès)]

Christopher Allan Webber <cwebber@dustycloud.org> skribis:

> David Thompson writes:
>
>> Ludovic Courtès <ludo@gnu.org> writes:
>>
>>> Christopher Allan Webber <cwebber@dustycloud.org> skribis:
>>>
>>>>  - The "hip new way" of doing things is to use Bower.  Bower is a
>>>>    package manager, but it's made specifically for static assets served
>>>>    to the user, such as css files, fonts, javascript like jquery, etc.
>>>>    Bower also puts these in an extlib/ or whatever, but it puts them in
>>>>    that place *for* you.
>>>
>>> Interesting.
>>>
>>> (Thinking out lout.)
>>>
>>> Just like ‘guix system vm’ returns a script that runs QEMU with the
>>> right arguments, one could imagine generating a script that copies
>>> dependencies in the right place maybe?
>>>
>>>   (define (make-installer assets)
>>>     (gexp->script "copy-assets"
>>>                   #~(begin
>>>                       (for-each copy-file '#$@assets)
>>>                       ...)))
>>>
>>> (This could/should be turned into a package object so that adding it as
>>> an input would drop it in $PATH.)
>
> The idea has me really excited.  But how do I make this happen, so that
> copy-assets appears in $PATH?  I am trying to do something with
> "guix environment" that does this, but I'm pretty confused as to how it
> could be done.

You would use a ‘web-assets’ procedure as Dave suggests, which would
return a package object that does the above and has the script in its
bin/ directory.

> How would you turn a gexp into a package object?  Would it just be a lot
> of package object stuff stubbed out?

Currently this is not automatic: one basically has to write a package,
typically using ‘trivial-build-system’ which is a thin wrapper around
gexps.

We should add a ‘gexp->package’ procedure.

>>> The developer would have to explicitly run that script to have the files
>>> copied under extlib/.
>>
>> That is a really neat use of gexps, and I guess running the script
>> manually would be akin to running 'bower install', so that should work.
>>
>> I envision the package recipe below, is this approximately what you were
>> describing?
>>
>>     (package
>>       (name "mediagoblin")
>>       (version "0.8.0")
>>       ...
>>       (inputs
>>        `(("python" ,python)
>>          ("assets" ,(web-assets jquery
>>                                 videojs
>>                                 bootstrap))))
>>       ...)
>
> Does web-assets generate that package object I assume?

Yes.

> I tried looking for examples of other package definitions that include
> derivations from gexps, and couldn't find anything clear...

Look for ‘trivial-build-system’.

> It also isn't clear to me: is it okay for (inputs) to include things
> that aren't packages?

Inputs can include packages, origins, derivations, and file names.

HTH!

Ludo’.