Earlier quoted context omitted.
Yeah, fuck this type safety and performance thing...
It's type safe and there's little performance hit. Please note that the "Interface" there is not "interface{}" ... it is a somewhat unfortunately named interface: http://golang.org/pkg/sort/#Interface The Go authors were following a practice that seemed like a good idea at first, and they've now admitted was probably a mistake... i.e. if your package is mostly about a single interface, name the package something info…
This Sort.Interface thing is indeed safe and performant. On the other hand its not a solution to the problem we're discussing (that, to quote the parent, due to lack of generics "it is tedious to write library code in the language"). You still have to implement it all the time for all types despite having identical implementations.
So this doesn't show how it's not tedious. It just shows that it can be done in some way, which nobody doubted.