Re: 'guix environment' as a build tool.

[Mathieu Lirzin]

"Thompson, David" <address@hidden> writes:

> On Sat, Jul 30, 2016 at 10:05 PM, Mathieu Lirzin <address@hidden> wrote:
>> address@hidden (Ludovic Courtès) writes:
>>
>>> Mathieu Lirzin <address@hidden> skribis:
>>>
>>>> I have tested successfully with the following command on a foreign
>>>> system:
>>>>
>>>>   guix environment --ad-hoc automake pkg-config guile guix libgcrypt 
>>>> sqlite guile-sqlite3
>>>>
>>>> Tell me if it works for you.
>>>>
>>>>> How about including a guix package definition then we can easily build
>>>>> it assuming "we" know how to do out-of-guix-tree package building :)
>>>>
>>>> It would indeed be nice to provide an easy way for Guix users to install
>>>> Cuirass.  IMHO package definitions meant as a development build tool is
>>>> confusing and should be avoided.  Nonetheless, I think it is useful to
>>>> document the previous 'guix environment ...' command in the README.
>>>
>>> What about providing a ‘guix.scm’ file that people could pass to ‘guix
>>> environment -l’ (instead of typing the long command above), and to ‘guix
>>> package -f’ (info "(guix) Invoking guix package")?
>>
>> 'guix environment -l' uses a package definition.  To me this abstraction
>> doesn't fit well in a development context:
>
> It *does* fit well.  This use-case is why I wrote 'guix environment'
> in the first place.

Obviously I disagree.

>>  - the origin hash doesn't make sense.
>
> You don't need one.  Use local-file for the source field.

I would be happy to, however I vaguely remember trying this without
success for Mcron.  Do you have an example to provide?

>>  - packages already included in Guix have redundant description and synopsis.
>
> I don't understand what this means.
>
>>  - package definitions rely on Guix internals.
>
> The package API rarely changes in practice.

This is relative, IME packages moving across modules is not an
exception.

>> In fact what 'guix.scm' contains feels more like a "debian" directory or
>> a "PACKAGE.spec" file on steroid because of the "guix environment -l"
>> feature which derives from it but doesn't appear as first class.
>>
>> An idea that I like better and is less invasive, would be to complement
>> bootstrap scripts with:
>>
>>   ./bootstrap --with-guix
>>
>> This command would:
>>
>> - generate a guix-env script that wraps 'guix environment ...' if it
>>   doesn't exist.
>> - Invoke ./guix-env
>> - Invoke autoreconf -vfi
>>
>> if the user wants to enter this environment Later it will have to invoke
>> './guix-env'.
>
> This just makes things more inconvenient and limits potential utility.
> You would lose the ability to tweak the dependency graph with custom
> package recipes.
>  I do this frequently in my projects that use bleeding edge features
> of other software that may not even have an official release yet.

Since this script is supposed to be wrapper around 'guix environment' I
don't understand how it could limit anything 'guix environment' could
do?

> Also, with a package file, Guix users can install the development
> snapshot with 'guix package -f' or simply build it with 'guix build
> -f'.

I am not sure what you mean by "development snapshot". If you an
arbitrary timely chosen commit like what is done for Haunt:

  (origin
    (method git-fetch)
    (uri (git-reference
         (url "git://dthompson.us/haunt.git")
         (commit "f0a7c2b14a201448432d3564d851ee0686d5b1b1")))
         (sha256
          (base32
           "1dnzsw18blhr8admw48zbl3ilz3iiqmb149i37y820h0imqfli0v"))))

This is not useful for me.  In most case I want 'guix build -f' to build
the current commit from the local repository.  If 'local-file' can work
then this is fine, but I have never achieved the expected result.

>> Some interesting things could be done beyond this, for example by using
>> per repository profiles that would save development environments.  This
>> would allow developpers to easily use different setups.
>
> 'guix environment' already serves this purpose.
>  I do want to extend 'guix environment' with a --save flag that will
> register the profile it generates as a GC root so that it can be saved
> for future sessions so that the environment doesn't need to be rebuilt
> every time the user upgrades Guix.

That would be nice.

> Hopefully this clears things up

Maybe I am misinterpreting, but this read a bit patronizing.  No need to
say that if this is the case I don't appreciate much.

-- 
Mathieu Lirzin