High Order Function with Type Parameter

[keean]

@shelby3

...the trait NatPos : Nat + Pos nominal intersection should no longer be supported in my proposal and thus the only way to call any methods on a Nat /\ Pos is to destructure it with pattern matching (which is not extensible) or to call trait implementations that exist for both Nat and Pos via a dynamic dispatch (which is extensible but ostensibly will require a global hashmap dictionary). I will detail this proposal more later.

I am sure you have some differences in mind, but a non-extensible tagged union is an Enum, and calling trait implementations that exist for both Nat and Pos is what "Nat + Pos" means, and you get dynamic dispatch from trait-objects.