While having to declare the interfaces a type implements can increase the readability, it comes with a huge drawback: you are limited to implementing the interfaces considered when writing the code. In my eyes it is a fascinating and important feature that you can add interfaces and all existing types automatically implement them, if they, by their methods signature, implement them. You don't have to edit their type declarations to do that.
>it comes with a huge drawback: you are limited to implementing the interfaces considered when writing the code
Huge drawback? Quite the opposite. Unintentional implementation is a terrible trade for readability and type-safety, hence the trick the prior commenter mentioned.
In fact, structural typing is best when limited to the far less used case where an interface is designed to reflect functions from existing types. It's useful here, otherwise it's a hinderance for the primary case where a type _intends_ to implement an interface, which is what nominal typing is for.
Go was designed as a systems language, and the choice for structural typing served that goal in terms of performance enhancements. But used as a general purpose language, as the trick above (and others) demonstrate, Go's structural typing is less suitable compared with nominal typing.
