Thank you for your answer. I was writing from the phone and didn't make myself clear. My question is: what are the legitimate use cases for interfaces that are half-nil?
Ignoring the compatibility guarantee for the sake of discussion, I feel that nobody would notice if the compiler tomorrow started short-circuiting the equality check of interfaces against nil to return true if either tuple value is nil. But maybe I'm missing some use-case.
> My question is: what are the legitimate use cases for interfaces that are half-nil?
I think that's two different questions:
* Is there a legitimate use case for nil not being nil? I don't think so.
* Is there a legitimate use case for having "typed nil" interfaces? Kinda, Go supports and encourages calling methods "with nil receivers", and doing that through an interface requires that the concrete type (the non-nil half) be conserved otherwise you can't dispatch the method call.
