"guix pack -f docker" does too much work

[Ricardo Wurmus]

Hi Guix,

a few months ago "guix pack -f docker" was modified to produce layers.
This is great!  Unfortunately, "guix pack" itself still produces one big
tarball containing all these layers.  There is no sharing of previously
built layers, because they are all hidden inside the pack.

I think it would be great if "guix pack -f docker" could avoid building
all these identical layers again and again.  Perhaps it would be
possible to have a single derivation for each layer?  This way we
wouldn't have to recreate the same layer archives every time.

What do you think?

-- 
Ricardo