Dear guix developers, Mathieu,

Please find attached a first version of the cachefilesd service patch.
The second patch for documentation will be sent right after.

I have a few general newbie scheme questions:

- I gathered that #~ / #$ kinds of suspends evaluation / forces it -- is
  there documentation about this somewhere ?

- There's something that looks like a splat operator (only seen in
  conjuction with forcing evaluation in #$@) -- again i'd be interested
  in more documentation about this feature -- is this a guix-specific
  operator?

- I don't understand why there are ^L separating services in the scheme
  files -- is this necessary? A convention? What purpose does it serve?

Regarding the patch itself:

- i'm not entirely sure the service belongs to services/linux.scm

- documentation is hastily written. I have found no way to indent
  automatically the lisp code in the texi file, which is very painfull
  -- would there be an emacs solution for this?

- there are no automated tests (beyond what I have done by hand
  locally!), and there's no lint, so I don't really feel confident about
  it :) Are there tests for services to alleviate my fears?

- I've copied some other service for modprobing the required kernel
  modules before launching the daemon with a one-shot shepherd
  service. Frankly i'm not happy about this solution, it seems to me
  that it unnecessarily pollutes the shepherd configuration; maybe some
  other mechanism (graft?) adjusting the modprobe configuration could be
  better (better still, autoload the file). Any guidance would be nice
  (including, that this solution is sufficient for now :))

I had great fun writing this, it reminded me of writing cookbooks during
my 'Chef' days. I must confess that the Chef DSL embedded in ruby seemed
more concise, and that it provided a way to write a cookbook
'out-of-tree' which was kind of less daunting for newcomers; however
it's already amazing that you have this kind of functionality!

Kind regards,
Jean-Baptiste