Generics Unconstrained! - Roger Peppe 

This talk explores some ways that Go's previous generic functionality (interfaces, closures) can make life easier in the brave new world of type parameters. By the end of the talk, you should come away with a better understanding of how type parameters can work together with other Go language features and some rules of thumb about when to use constraints.
Much of the complexity of the new generics feature comes from the use of constraints, particularly structural constraints.