I think what has been proposed so far is powerful enough to perform that
task *if* there is an intermediate object in the mix.
if (
// Assuming a dual pattern for JsonString.of and the SAP
// strategy outlined in the doc
json instanceof index(0, JsonString::of).decode(var firstName)
) {
}
On Wed, May 21, 2025 at 1:26 PM Maurizio Cimadamore <
[email protected]> wrote:
>
> On 21/05/2025 18:06, Paul Sandoz wrote:
>
> It was a design choice to be consistent with each json value having an
> X, accepting X in on construction and producing X out (notionally) on
> deconstruction, which leans into pattern matching. Definitely pros/cons
> to that e.g., we could instead make JonObject implement Map, or do as
> you suggest [*], both of which adjust how one reasons about the X in and
> X out.
>
> I agree with this. When I wrote, I thought that it might be possible to
> address some of these use cases using instance pattern declaration on the
> array class (e.g. having an instance pattern that extracts the i-th element
> of a JSONArray) -- but the instance pattern proposals we have discussed so
> far [1] are not powerful enough to model that use case.
>
> Maurizio
>
> [1] -
> https://openjdk.org/projects/amber/design-notes/patterns/towards-member-patterns
>
