[swift-evolution] Proposal: An Either Type in the STL

[Matthew Johnson]

> 
> Generics.
> 
> Also, what are the proposed injection / projection / conversion rules for structural sums?  Implicit injection and dynamic cast, as if it were an existential type?

Thanks for pointing out the issues that need clarification.  It will give me some things to think about in the coming days.  

Can you elaborate on generics a bit?  Do you mean generic structural sum types, structural sum types with cases containing generic types, or both?