[swift-evolution] [swift-evolution-announce] [Review] SE-0142: Permit where clauses to constrain associated types

[Howard Lovatt]

> The review of SE-0142: "Permit where clauses to constrain associated types" begins now and runs through September 30, 2016. The proposal is available here:
> https://github.com/apple/swift-evolution/blob/master/proposals/0142-associated-types-constraints.md

> What is your evaluation of the proposal?
It is a valuable addition to Swift and certainly something I have desired. However I feel the proposed syntax is long winded, something associated types already suffer from. There also seems to be an inconsistency in specifying constraints sometimes in where clauses and other times as a constraint on the associated type. 

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

> Does this proposal fit well with the feel and direction of Swift?
Not quite. See above. 

> If you have used other languages or libraries with a similar feature, how do you feel that this proposal compares to those?
It is similar to generics and begs the question why not abandon associated types and just have generics on protocols. 

> How much effort did you put into your review? A glance, a quick reading, or an in-depth study?
Mainly my comments are based on writing my own collection library in Swift and comparing that exercise to similar in Java and C++. It is at the moment significantly harder than in Java but easier than C++. Any improvement in associated types would be welcome. 
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