[swift-evolution] Support for pure setters

[Chris Lattner]

> On Jan 8, 2016, at 10:45 AM, David James via swift-evolution <swift-evolution at swift.org> wrote:
> 
> Let me ask you this. If the drawbacks in implementation did not exist, would this be an improvement worth adding?

These are drawbacks in design, not implementation. Swift fundamentally assumes that something mutable can also be read.  Making the model more complex to serve a very narrow use case is not worth it.

> My sense is yes, since it fills out functionality already half-way there (via private(set)).

I see it the opposite way: private(set) gets you so close that there is even less reason to do something here.

-Chris