> On 24 Sep 2016, at 21:58, Drew Crawford via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> This is the #1 Swift feature I have wanted for the past 2 years.
>
> One thing I would like to see (perhaps out of scope for this proposal) is the
> natural extension for generic parameters:
>
> struct Box<T> {
> var t: T
> }
>
> extension Box where T == Int { //error: Same-type requirement makes generic
> parameter T non-generic
> }
>
> There is a great deal of overlap between associated types and generic
> parameters, and it seems to me that it would be favorable to allow `==` with
> both generic parameter operands and associatedtype operands for consistency.
>
> Drew
>
I think this is already part of the Generics Manifesto:
https://github.com/apple/swift/blob/master/docs/GenericsManifesto.md
> Concrete same-type requirements
>
> Currently, a constrained extension cannot use a same-type constraint to make
> a type parameter equivalent to a concrete type. For example:
>
> extension Array where Element == String {
> func makeSentence() -> String {
> // uppercase first string, concatenate with spaces, add a period, whatever
> }
> }
> This is a highly-requested feature that fits into the existing syntax and
> semantics. Note that one could imagine introducing new syntax, e.g.,
> extending Array<String>, which gets into new-feature territory: see the
> section on "Parameterized extensions".
>
- Karl
> On September 23, 2016 at 6:51:51 PM, Douglas Gregor (dgre...@apple.com
> <mailto:dgre...@apple.com>) wrote:
>
>> Hello Swift community,
>>
>> 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
>>
>> <https://github.com/apple/swift-evolution/blob/master/proposals/0142-associated-types-constraints.md>
>> Reviews are an important part of the Swift evolution process. All reviews
>> should be sent to the swift-evolution mailing list at
>>
>> https://lists.swift.org/mailman/listinfo/swift-evolution
>> <https://lists.swift.org/mailman/listinfo/swift-evolution>
>> or, if you would like to keep your feedback private, directly to the review
>> manager. When replying, please try to keep the proposal link at the top of
>> the message:
>>
>> Proposal link:
>>
>> https://github.com/apple/swift-evolution/blob/master/proposals/0142-associated-types-constraints.md
>>
>> <https://github.com/apple/swift-evolution/blob/master/proposals/0142-associated-types-constraints.md>
>> Reply text
>>
>> Other replies
>>
>> <https://github.com/apple/swift-evolution/pull/532#what-goes-into-a-review-1>What
>> goes into a review?
>>
>> The goal of the review process is to improve the proposal under review
>> through constructive criticism and, eventually, determine the direction of
>> Swift. When writing your review, here are some questions you might want to
>> answer in your review:
>>
>> What is your evaluation of the proposal?
>> Is the problem being addressed significant enough to warrant a change to
>> Swift?
>> 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?
>> How much effort did you put into your review? A glance, a quick reading, or
>> an in-depth study?
>> More information about the Swift evolution process is available at
>>
>> https://github.com/apple/swift-evolution/blob/master/process.md
>> <https://github.com/apple/swift-evolution/blob/master/process.md>
>> Thank you,
>>
>> -Doug Gregor
>>
>> Review Manager
>>
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