bug#38529: Make --pure the default for `guix environment'?

[Taylan Kammer]

On 10.12.2019 18:16, Ludovic Courtès wrote:
> Hello!
>
> "Thompson, David" <dthompson2@worcester.edu> skribis:
>
> > I have long thought that --ad-hoc should be implied, as that is the
> > mode I use 99% of the time, but I disagree that --pure should be the
> > default.
>
> I very much agree with that.  I don’t think ‘--pure’ should be the
> default, because there are valid use cases for that.
>
> As for ‘--ad-hoc’: making it the default is technically easy.  The
> difficulty is to come up with a nice transition/deprecation mechanism so
> that we don’t break everyone’s script overnight.
>
> Ideas on how to achieve it are welcome!
>
> Thanks,
> Ludo’.

I suppose the straightforward way of doing such a transition would be:

- In the next release, add --inputs-of and make the use of 'guix 
environment' with neither switch emit a warning saying you should use 
the new switch to explicitly enable it because the default will change.

- Later, change the default behavior and deprecate --ad-hoc as it 
becomes a no-op.

- (Optional) In some future release, remove --ad-hoc.


Taylan