I know next to nothing about Go, but I think you're referring to the fact that it has some sort of implicit inheritance resolution - if there is a Reader interf

I know next to nothing about Go, but I think you're referring to the fact that it has some sort of implicit inheritance resolution - if there is a Reader interface with a read method, and a type A that has a read method with the same signature, then A will be considered to be a subtype of Reader, whether you marked it as such (or whether you want it or not). I see what you mean, this feels like a static version of duck typing. I'm not sure how I feel about loosing control over what supertypes my type extends, though - well, I lie. I don't like it. But I haven't given this enough thought for a constructive, well argumented discussion on the topic.