[swift-evolution] where clauses on enum cases

[Joe Groff]

> On Mar 14, 2017, at 12:58 PM, Slava Pestov via swift-evolution <swift-evolution at swift.org> wrote:
> 
> You’re asking for GADTs: https://en.wikipedia.org/wiki/Generalized_algebraic_data_type
> 
> This feature is difficult to implement correctly and efficiently and I doubt Swift will ever support it, but you never know…

We'll already have most of the same problems with existentials, so I don't think it's unreasonable to support this at some point in the future. Not necessarily the *near* future, of course.

-Joe