Yeah, 'class' in Bon defines a typeclass. While I plan on adding x.norm() as syntactic sugar for norm(x), typeclasses in general are a bit more flexible. For example, while you can use it for polymorphic operator overloading [0], you can also overload a function by changing the types of multiple parameters [1] (as in multiple dispatch).
[0] https://github.com/FBMachine/bon/blob/master/examples/equali...
[1] https://github.com/FBMachine/bon/blob/master/examples/multip...