But you never want a generic implementation of a data structure. You want concrete implementations of data structures. I have written Go for over 6 years now an

But you never want a generic implementation of a data structure. You want concrete implementations of data structures. I have written Go for over 6 years now and written many hundred thousand lines of code. The time I'd save avoiding writing concrete data structures would probably not even be measurable. There are simply other areas of programming that dominate time. Having written so much Go code, there were situations where generics would have been useful, but they were of a very different kind. Generics and typed unions would be very helpful for writing compilers (what I do). But even then it's a matter of making code clearer and and more type safe, rather than saving time/not writing data structures. Other than compilers I have never felt the need of generics in Go, and I have never felt the need to write data structures containing interface{}. interface{} is very useful as a parameter type, to reflect on it, but it's almost always a mistake to use it inside a data structures (there are exceptions, but people usually abuse it). There's no question that some form of generics would be useful to some people in some context, but its necessity is overblown.