I'm not sure exactly where the bar is, but chiming in that recently, in implementing generic succinct data structures as an exercise, I needed to define exactly this operation generically.<br><br>-Colin<br><div class="gmail_quote"><div dir="ltr">On Tue, Feb 21, 2017 at 6:29 PM Max Moiseev via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg">On Feb 21, 2017, at 3:05 PM, Howard Lovatt via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="gmail_msg" target="_blank">swift-evolution@swift.org</a>> wrote:</div><br class="m_5571788980976172498Apple-interchange-newline gmail_msg"><div class="gmail_msg"><div class="gmail_msg">The re-review of SE-0104 "Protocol-oriented integers" begins now and runs through February 25, 2017. This proposal was accepted for Swift 3, but was not implemented in time for the release. The revised proposal is available here:<br class="gmail_msg"><div class="gmail_quote gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><br class="gmail_msg"><span class="m_5571788980976172498m_-2917819102280157209Apple-tab-span gmail_msg" style="white-space:pre-wrap"> </span><a href="https://github.com/apple/swift-evolution/blob/master/proposals/0104-improved-integers.md" class="gmail_msg" target="_blank">https://github.com/apple/swift-evolution/blob/master/proposals/0104-improved-integers.md</a><br class="gmail_msg"><br class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"><div class="gmail_msg"><span class="m_5571788980976172498m_-2917819102280157209Apple-tab-span gmail_msg" style="white-space:pre-wrap"> </span>• What is your evaluation of the proposal?</div></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Well worth while. Few nit picks:</div><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg"><div class="gmail_msg"> 1. Number.init? Description should say BinaryInteger not floating-point.</div></div></div></div></div></blockquote></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg">I’ll update the proposal.</div><div class="gmail_msg"></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"><div class="gmail_quote gmail_msg"><div class="gmail_msg"><div class="gmail_msg"> 2. Number should document that mutating versions of operators can overflow.</div><div class="gmail_msg"> 3. SignedNumber should document that negate and unary `-` can overflow.</div></div></div></div></div></blockquote></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg">Documentation changes noted. Thanks!</div><div class="gmail_msg"></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"><div class="gmail_quote gmail_msg"><div class="gmail_msg"><div class="gmail_msg"> 4. SignedNumber, it is weird that `signum` is a function when other similar things, e.g. `magnitude`, are properties.</div></div></div></div></div></blockquote></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg">I think of it as: magnitude is something the number ‘has’ whereas signum is a completely new thing of the same type.</div><div class="gmail_msg"></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"><div class="gmail_quote gmail_msg"><div class="gmail_msg"><div class="gmail_msg"> 5. Not worth representing `DoubleWidth` as an enumeration, it is obscure and therefore will only confuse people.</div><div class="gmail_msg"> 6. It would be better to put the 'extra' operations into the protocols and provide default implementations, otherwise they are difficult to find. </div></div></div></div></div></blockquote></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg">They are defined as protocol extensions, therefore they should be discoverable through completion and in the generated source code. Or what do you mean by ‘difficult to find’?</div><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Thanks for the feedback!</div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"><div class="gmail_quote gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg"><span class="m_5571788980976172498m_-2917819102280157209Apple-tab-span gmail_msg" style="white-space:pre-wrap"> </span>• Is the problem being addressed significant enough to warrant a change to Swift?</div></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Yes, the current design has not served my purpose on more than one occasion </div><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg"><span class="m_5571788980976172498m_-2917819102280157209Apple-tab-span gmail_msg" style="white-space:pre-wrap"> </span>• Does this proposal fit well with the feel and direction of Swift?</div></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Yes</div><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg"><span class="m_5571788980976172498m_-2917819102280157209Apple-tab-span gmail_msg" style="white-space:pre-wrap"> </span>• If you have used other languages or libraries with a similar feature, how do you feel that this proposal compares to those?</div></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Yes, this proposal is similar to what other languages provide, e.g. Scala. In Scala however they tackle the `conversion problem as well in their `traits heirarchy. I guess this could be added at a later date.</div><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg"><span class="m_5571788980976172498m_-2917819102280157209Apple-tab-span gmail_msg" style="white-space:pre-wrap"> </span>• How much effort did you put into your review? A glance, a quick reading, or an in-depth study?</div></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"></div></div></div></blockquote><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"></div></div></div></blockquote><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"></div></div></div></blockquote><div class="gmail_msg">Read the proposal, have used similar features in other languages, and have had trouble with Swift's current heirarchy. </div></div></div><div dir="ltr" class="gmail_msg">-- <br class="gmail_msg"></div><div data-smartmail="gmail_signature" class="gmail_msg">-- Howard.</div>
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