Re: We need to add role annotations for 7.8

[Sorry for the self-reply.] Oh, perhaps I actually understand this:

Please forgive my ignorance w.r.t. roles, but why aren't all of these representational?

...

Map k v -- k: nominal, v: represententional Set a -- k: nominal

AFAIK both Map and Set are "normal" datatypes. Not GADTs, no type families involved. Why would anything need to be "nominal" then?

Is this because the integrity of these types relies on the Ord instance being sane, and a newtype could have a different Ord instance defined? Cheers, Andres