[swift-evolution] [Review] SE-0081: Move where clause to end of declaration

Thorsten Seitz tseitz42 at icloud.com
Thu May 12 12:43:11 CDT 2016

> Am 10.05.2016 um 20:51 schrieb Chris Lattner via swift-evolution <swift-evolution at swift.org>:
> Hello Swift community,
> The review of "SE-0081: Move where clause to end of declaration" begins now and runs through May 16. The proposal is available here:
> 	https://github.com/apple/swift-evolution/blob/master/proposals/0081-move-where-expression.md
> 	* What is your evaluation of the proposal?


It increases readability of generics by a far margin.
I appreciate that the proposal allows to pull out the inheritance/conformance constraints into the where clause, too, very much!

> 	* Is the problem being addressed significant enough to warrant a change to Swift?

Yes, as more complex generics are a powerful feature of Swift and the increased readability helps designing and using them very much.

> 	* Does this proposal fit well with the feel and direction of Swift?


> 	* If you have used other languages or libraries with a similar feature, how do you feel that this proposal compares to those?

Ceylon uses a similar syntax to declare the constraints of generic parameters:
shared interface DirectedGraph<V,E> satisfies IncidenceGraph<V,E>
      given V satisfies Object
      given E satisfies DirectedEdge<V, E> { … }
I always found this very readable but with Swift’s ability to declare constraints between associated types of generic parameters this is even more important.

> 	* How much effort did you put into your review? A glance, a quick reading, or an in-depth study?

Read the proposal carefully and followed the discussion.


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