Re: Why does to_json take "anyelement" rather than "any"?

On Thu, Nov 5, 2020 at 3:43 PM Mohamed Wael Khobalatte <
mkhobalatte(at)grubhub(dot)com> wrote:

> You can always cast to text yourself, of course, but I am not familiar
> with the type hierarchy enough to tell why `to_json` can't deduce that as
> text whereas the other function can.
>

My understanding is that "any" is defined to accept that behavior -
allowing any pseudo-type and unknown. The "anyelement" polymorphic
pseudo-type is defined such that only concrete known types are allowed to
match - and then the rules of polymorphism apply when performing a lookup.
My uninformed conclusion is that since to_json only defines a single
parameter that changing it from "anyelement" to "any" would be reasonable
and the hack describe probably "just works" (though I'd test it on a
wide-range of built-in types first if I was actually going to use the hack).

You only get to use "any" for a C-language function but that is indeed the
case here.

David J.