I think the reason Go is usable compared to early Java is because it does have generics for the builtin types -- slices (growable arrays), maps, and channels --

I think the reason Go is usable compared to early Java is because it does have generics for the builtin types -- slices (growable arrays), maps, and channels -- and for the builtin functions that operate on these types. And you can get really far with just slices and maps (which double as sets). You just can't add your own generic types or functions.