What exactly isn’t a language feature? Or do you have issues with semantics? var _ Foo = (*Bar)(nil) The statement asserts that Bar struct pointers are as

What exactly isn’t a language feature? Or do you have issues with semantics? var _ Foo = (*Bar)(nil) The statement asserts that Bar struct pointers are assignable to a Foo interface. I do agree it’s not as clean looking as the Java implements keyword, but it’s already a fairly terse pattern and IMO the inconvenience does not justify introducing new language syntax.