[swift-evolution] [Pre-Proposal-Discussion] Union Type - Swift 4

[Tino Heth]

Hi Cao,

Considering "&" for types is already decided, symmetry would be enough motivation for me to add "|" as well.

Maybe I would even support replacing enums with associated values in favor of union types (my impression is that enums aren't as useful as I thought when I started using them).

But right now, this doesn't seem to be a time for discussing huge changes, but for actually implementing smaller ones ;-)
I'm a little bit concerned that Swift might already be preferring compatibility over elegance, but the defensive attitude that you perceived might as well be explained with release-stress…

Of course, rejection is still frustrating — but please consider that most proposals aren't accompanied by an implementation, so every wish that's accepted adds something to the pile of work to be done by the core team.
Imho it would be nice if Swift evolution would be more "decentralized", moving away from proposals like "I want to have feature X" towards "I want to develop feature X, is there a chance this could be integrated?", but coordination is already hard enough, so this might be unfeasible.

- Tino