Personally I find typealias useful for giving a friendly name to long types and informative names to types in general. This applies to generic types as much as non-generic, e.g.:<div><br></div><div> typealias Vec4<T: Numerical> = (T, T, T, T)</div><div> typealias Mat4<T: Numerical> = (Vec<T>, Vec<T>, Vec<T>, Vec<T>)</div><div><br></div><div>Further I would like to be able to add additional constraints that are not part of the rhs of the alias, e.g.:</div><div><div><br></div><div> typealias VecSparse<T: Numerical> = Dictionary<Int, T></div><div> typealias MatSparse<font size="2"><span style="background-color:rgba(255,255,255,0)"><T: Numerical> = Dictionary<Int, VecSparse<T>></span></font></div><br>On Friday, 25 March 2016, Dave Abrahams via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
on Thu Mar 24 2016, Douglas Gregor <dgregor-AT-apple.com> wrote:<br>
<br>
> Hello Swift community,<br>
><br>
> The review of SE-0048 "Generic Type Aliases" begins now and runs through March 29, 2016. The proposal is available here:<br>
><br>
> <a href="https://github.com/apple/swift-evolution/blob/master/proposals/0048-generic-typealias.md" target="_blank">https://github.com/apple/swift-evolution/blob/master/proposals/0048-generic-typealias.md</a><br>
> Reviews are an important part of the Swift evolution process. All reviews should be sent to the swift-evolution mailing list at<br>
><br>
> <a href="https://lists.swift.org/mailman/listinfo/swift-evolution" target="_blank">https://lists.swift.org/mailman/listinfo/swift-evolution</a> <<a href="https://lists.swift.org/mailman/listinfo/swift-evolution" target="_blank">https://lists.swift.org/mailman/listinfo/swift-evolution</a>><br>
> or, if you would like to keep your feedback private, directly to the<br>
> review manager. When replying, please try to keep the proposal link at<br>
> the top of the message:<br>
><br>
> Proposal link:<br>
><br>
> <a href="https://github.com/apple/swift-evolution/blob/master/proposals/0048-generic-typealias.md" target="_blank">https://github.com/apple/swift-evolution/blob/master/proposals/0048-generic-typealias.md</a><br>
> Reply text<br>
><br>
> Other replies<br>
> <<a href="https://github.com/apple/swift-evolution#what-goes-into-a-review-1" target="_blank">https://github.com/apple/swift-evolution#what-goes-into-a-review-1</a>>What goes into a review?<br>
><br>
> The goal of the review process is to improve the proposal under review<br>
> through constructive criticism and, eventually, determine the<br>
> direction of Swift. When writing your review, here are some questions<br>
> you might want to answer in your review:<br>
><br>
> What is your evaluation of the proposal?<br>
><br>
> Is the problem being addressed significant enough to warrant a change<br>
> to Swift?<br>
<br>
That's my biggest question about this proposal. Yes, as the proposal<br>
says, generic type aliases fill an obvious functional gap. But what<br>
real-world problems are they solving and why should adding them be a<br>
priority?<br>
<br>
--<br>
Dave<br>
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</blockquote></div><br><br>-- <br>-- Howard.<br>