Re: Syntactic Diabetes (was Re: A friendlier API for operating-system declarations)

["Ludovic Courtès" <ludo@gnu.org>]

Hello!

Edouard Klein <edou@rdklein.fr> skribis:

> Thank you Liliana and Attila for the swift and actionable feedback :)
>
> Below is a revised proposition.
>
> Here is a minimal working example of an os declaration:
> ------------------mwe.scm---------------
> (use-modules
>  (beaver system)
>  (beaver functional-services)
>  (gnu packages version-control)
>  (gnu services web)
>  (gnu services telephony)
>  (gnu services ssh)
>  (gnu services base)
>  (guix gexp))
>
> (-> (minimal-ovh "osef")
>     (instantiate nginx)
>     (instantiate mumble-server
>                  (welcome-text "coucou")
>                  (port 64738))
>     (extend openssh `(("alice" ,(local-file "/home/edouard/.ssh/id_rsa.pub"))))
>     (modify openssh
>             (password-authentication? #f)
>             (allow-empty-passwords? #t))
>     (remove guix))
> -------------------------------------------------------
>
> To see the value of this syntactic sugar, try to replicate this MWE with
> the standard syntax. It's not horrendous, but it *is* off-putting to
> many newcomers to git, whereas this sugary piece is more readable for
> them (sample size of 1, p=0.00000005).

Glad you ran a user study.  :-)

This is looking more and more like:

  (define-syntax ->
    (syntax-rules ()
      ((_ os rules ...)
       (operating-system
         (inherit os)
         (services (modify-services (operating-system-user-services os)
                     rules ...))))))

One thing that always makes me hesitate due to the longstanding hygienic
macro tradition in Scheme is non-hyienic introduction of identifiers: in
the example you gave above, the identifiers ‘openssh-service-type’ and
‘openssh-configuration’ are automatically derived from ‘openssh’.  This
could lead to surprises and makes grepping harder.  But I don’t know,
maybe that’s the price to pay?

Maybe one conclusion we can draw from this is that configuration records
and service types should be more closely tied to one another.

>>> (service+ OS SERVICE [CONF])
>>> (service- OS SERVICE)

This one looked really revolutionary, but it’s inspiring too!

Thanks,
Ludo’.