So you're saying you'd prefer it if you had to explicitly tell Go that your type implements an interface? Something like this?

  type Shape interface {
      Area() int
  }

  type Square struct {
     sideLen int
  }

  // Somehow denote that this function is implementing
  // Shape's Area function
  func (s Square) Shape.Area() int {
      return sideLen * sideLen
  }

Because, one of the things I like best about Go's interfaces is that you don't have to do that.