Hi Nils,

On 2023-11-26 11:14, Nils Landt wrote:
> Bruno:
>> This isn't needed, fields whose maybe-values are unset don't call the
>> serializing procedures.
> 
> combined with
> 
>> You can use 'serialize-configuration' instead which accounts for the unset maybe-values.
> 
> I put some time into this, but I don't see how serialize-configuration, which returns a gexp including string-append, could be used to turn a configuration record into the format required by guile-json.

Right, I missed that you are synthesizing a list for scm->json,
you will need to make use of the lower-level transducers in
(gnu services configuration).
The fstrim-service-type in (gnu services linux) provides a simple
example of its use though for your case you might be looking at
something like:

--8<---------------cut here---------------start------------->8---
;; note: untested snippet

(define (goimapnotify-files config)
  (match-record config <home-goimapnotify-configuration>
                (accounts)
    (map (match-lambda
           ((path account)
            (list path
                  (computed-file
                   (string-append "mail-imapnotify-config-"
                                  (goimapnotify-account-host account))
                   (with-extensions (list guile-json-4)
                     #~(begin
                         (use-modules (json builder))
                         (with-output-to-file #$output
                           (lambda ()
                             (scm->json
                              (list #$@(list-transduce
                                        (base-transducer account)
                                        rcons
                                        goimapnotify-account-fields)))
                             #:pretty #t))))))))
         accounts)))
--8<---------------cut here---------------end--------------->8---

-- 
Furthermore, I consider that nonfree software must be eradicated.

Cheers,
Bruno.