Hi! Maxim Cournoyer <maxim.courno...@gmail.com> skribis:
> Since commit 8cb1a49a3998c39f315a4199b7d4a121a6d66449, the > define-configuration machinery in (gnu services configuration) uses > *unspecified* instead of 'disabled for an unspecified field value. As Attila wrote, the rationale as discussed in <https://issues.guix.gnu.org/54674> was to specifically use a “special” value without a read syntax in lieu of a symbol like 'disabled. > While this is indeed an improvement in readability, it introduces an > extra complication: because this new value is not self-quoting, it > cannot be used as is in G-Exps, and values using it must be carefully > expanded outside the gexp context, which is error prone. Could you give a simple example of how this can happen? In my experience, one would use ‘define-maybe’ and appropriate field serializers such that *unspecified* never goes through. Previously you’d check for (eq? x 'disabled) and now you just check for (unspecified? x). Thanks, Ludo’.
