I'll agree with the opinion that it can be confusing that an interface consists of two elements, the type and the value itself, and that the "== nil" check may not do what you initially expect, because the interface values are hidden below the surface of the abstraction the language provides. But it is not true to say that "the interface value is nil", because it factually isn't. To use psuedo-Go, since neither "Interface" nor the types are first-class values, Interface{ConcretePointerType, nil} does not and should not compare as equal to nil. There are values in memory corresponding to this interface value, and those values do not correspond to any interpretation of "nil" Go uses. We're talking about real numbers in real RAM here and a real specification of nil that corresponds to those real numbers in RAM; this is not a matter of opinion.

I don't know of any language that doesn't have a few dozen quirks of this sort buried in it. It can be pointed out as a legitimate criticism of the language, but it's not particularly a flaw relative to other languages. Either it's not possible to build a truly clean programming language that lacks this sort of quirk, or we're not very good at it.

Before replying to me with the language you believe lacks these quirks, please do me a favor and search for "$LANGUAGE quirk" and "$LANGUAGE gotcha" first, because that's the first thing I'm going to do. And it won't be a defense to me to explain how what you found is not really a quirk because you just have to properly understand the language, because that defense is true for this quirk of Go's too.