Re: Wrap %default-guix-channel inside channel-with-substitutes-available by default?

[Mathieu Othacehe]

Hello,

> I think we do have the obligation to clearly document channels-with-
> substitutes-available and make it so that this particular piece of
> documentation can easily be found by everyone who is potentially
> affected by slow-downs.  Perhaps we might even want to include an
> option in the installer to set up /etc/guix/channels.scm to only use
> channels with available substitutes.  But using it as a default without
> communicating this fact to the users would be a poor idea in my
> opinion.

I fear that a lot of users are not aware of this mechanism and do not
really understand why "guix pull" sometimes starts building stuff. 

We could maybe proceed this way:

1. Enable the channel-with-substitutes-available snippet by default.

2. Add a command line option --without-available-substitutes.

3. Add a new info message when the fetched commit is not the latest
commit, to minimize the risk you are mentioning above. Something like:

Skipping N new commits that do not have any available substitutes, use
the --without-available-substitutes option to update anyway.

WDYT?

Thanks,

Mathieu