Re: Making local development easy

[Alex Sassmannshausen <alex.sassmannshausen@gmail.com>]

Hello,

Christopher Baines writes:

> Today I had a go at writing a dummy python library, and packaging it,
> and then installing it within an environment, with the aim of
> experimenting more with how Guix works, and to explore how Guix can be
> used as a developer (with unpublished local packages).
>
> There were several slight issues with this, but I got some help on IRC
> to work around these.

I've definitely gone down the same route of wanting to use Guix in local
development.  At the moment I'm using
  guix environment -l project-guix.scm
to spawn a shell with the full working environment for my project — this
is awesome, but I think it's slightly orthogenal to what you describe.

> The first, is that the hash is required, which I only had to compute
> once, but if I wanted to change the package, I would have to update
> this, which is prohibitive to local development. As an improvement to
> this, could the hash be optional, and if it does not exist, be
> calculated when the build is performed?

From my perspective, I think silently calculating a hash on the fly if
it is not provided would be problematic: it might lead to laziness in
completing the hash, which would undermine the security model of Guix
(if I understand correctly).

But maybe an explicit flag setting the declaration to "dev-mode", might
be useful?

> The second issue was getting the data to the store, as first I tried a
> relative path, but that did not work, and ended up having to expose the
> repository using a HTTP server, and access it over the loopback
> interface. This again is rather prohibitive to local development. To
> improve on this, could guix build do the insertion in to the store, such
> that relative paths would work? This would allow just writing a
> "guix.scm" file, which just uses (git-reference (url "./") (commit "HEAD")).

This, I think, would be great.  Specifically, accepting a "file:///"
protocol for (uri)/(git-reference (url)) would be pretty useful…

My 2¢…

Alex