std.sumtype?

[Oleg B]

On Thursday, 18 March 2021 at 16:11:06 UTC, Paul Backus wrote:
> Something like this:
>
> alias QualifiedTypes = CopyTypeQualifiers!(typeof(val), 
> val.Types);
> auto tag = val.match!(v => staticIndexOf!(typeof(v), 
> QualifiedTypes));

why it is not in library? or why tag is private?