How can I test at compile time whether T is an instance of an interface ?

[data pulverizer]

On Wednesday, 23 September 2020 at 18:56:33 UTC, wjoe wrote:
>
> It doesn't occur to me that the compiler doesn't know at 
> compile time that
>
> interface IFoo{}
> class Foo: IFoo {}
>
> class Foo implements interface IFoo.

Didn't think that the compiler didn't know but wasn't aware that 
you could use that information to statically dispatch. My 
mistake, I'll shut up now!