Peter Eisentraut <peter(at)eisentraut(dot)org> writes:
> Maybe this could be written in such a way that it doesn't hardcode JSON
> arrays specifically, but a type could have an iteration helper function
> that would feed this feature?
+1. ISTM that this feature would make sense for subscriptable types,
so one way to shoehorn it into the system without a lot of new overhead
could be to extend struct SubscriptRoutines to offer optional support
function(s) for iterating through all the elements of a subscriptable
object.
regards, tom lane