Hi Leo,

About ordering:

1. ~/.config/guix/current is special in that it's the channel of Guix
and it's installed by "guix pull" unlike other channels.  Thus I don't
think it belongs to GUIX_PROFILE_DIR.  That said, we could introduce
another environment variable for those who want to move it somewhere
else.

2. Indeed profiles should be loaded in a well known order.  I suggest to
follow the C alphabetical order.  Should "default" be sourced before the
rest?  Maybe not.  I suggest we leave it to the user at this point.

> - When GUIX_PROFILE_DIR is set, use GUIX_PROFILE_DIR/channels in `guix
> pull', falling back to ~/.config/guix/current.

As suggested above, "guix pull" is quite special.  I don't think we
should put it in GUIX_PROFILE_DIR/channels.

> - When GUIX_PROFILE_DIR is set, read channels from
> $GUIX_PROFILE_DIR/channels.scm, falling back to
> ~/.config/guix/channels.scm.

No strong opinion here, we could also leave it to
~/.config/guix/channels.scm.  It's a configuration file after all.

>> - Add a "-P,--profile-name NAME" command line option that
>> automatically derives
>>   the profile path as $GUIX_PROFILE_DIR/$NAME.  This would make it
>> easy
>>   to deal with frequently-used profiles from command line, e.g.
>> 
>>   guix install -P my-gimpy-profile gimp
> Could we also make this accept absolute and relative paths (the latter
> prefixed with ./) to deprecate `guix environment -r'?

Maybe not, since this might raise confusions, e.g. what happens when you
type `-P my-profile` and there is a "my-profile" directory in the
current directory?

Thanks for the feedback!

Cheers!

-- 
Pierre Neidhardt
https://ambrevar.xyz/