<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><span style="font-size: 13px;" class="">Thank you for your comments. </span><div style="font-size: 13px;" class=""><br class=""></div><div style="font-size: 13px;" class="">I think additional index manipulation and collection scanning API is needed, and your proposal cover an important part of it.</div><div style="font-size: 13px;" class=""><br class=""></div><div class=""><span style="font-size: 13px;" class="">I also have some clarifications and comments inline:</span><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On May 10, 2016, at 4:52 PM, Nate Cook <<a href="mailto:natecook@gmail.com" class="">natecook@gmail.com</a>> wrote:</div><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Thanks Hooman! Those do look like useful extensions. I think the proposal should stay focused on the APIs it includes already.<div class=""><div class=""><blockquote type="cite" class=""><div class="">On May 10, 2016, at 4:18 PM, Hooman Mehr <<a href="mailto:hooman@mac.com" class="">hooman@mac.com</a>> wrote:</div><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div class=""><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">public</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">func</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">offset</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">(</span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">of</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-smi" style="box-sizing: border-box; color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">index</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">: Index) </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">-></span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> IndexDistance</span></div><div class=""><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">public</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">func</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">index</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">(</span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">atOffset</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-smi" style="box-sizing: border-box; color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">offset</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">: IndexDistance) </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">-></span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> Index</span></div></div></div></div></blockquote><div class=""><br class=""></div><div class="">I like these, but I doubt they would get much traction, since they're essentially substituting startIndex into existing methods. I have thought it would be nice to have startIndex as the default parameter to those methods, though, so you could write either of these:</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>let i = c.index(c.startIndex, offsetBy: 5)<span class="Apple-tab-span" style="white-space:pre"> </span>// current</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>let i = c.index(offsetBy: 5)<span class="Apple-tab-span" style="white-space:pre"> </span>// nice addition</div></div></div></div></div></blockquote><div style="font-size: 13px;"><br class=""></div><div style="font-size: 13px;">That is right. The main function is `offset` that I use a lot and for the reverse, your suggestion seems better. I am using `offset` quite a bit but I don’t know if it is generally as useful for other people as it is for me.</div><br class=""><blockquote type="cite" class=""><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div class=""><br class=""><blockquote type="cite" class=""><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div class=""><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">public</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">func</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">index</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">(</span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">of</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-smi" style="box-sizing: border-box; color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">element</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">: Iterator</span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">.</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">Element, </span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">from</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-smi" style="box-sizing: border-box; color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">firstIndex</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">: Index) </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">-></span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> Index?</span></div><div class=""><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">public</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">func</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">index</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">(</span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">from</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-smi" style="box-sizing: border-box; color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">firstIndex</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">: Index, </span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">where</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-smi" style="box-sizing: border-box; color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">predicate</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">: </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">@noescape</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> (Iterator</span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">.</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">Element) throws </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">-></span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-c1" style="box-sizing: border-box; color: rgb(0, 134, 179); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">Bool</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">) rethrows -> Index?</span></div></div></div></div></blockquote><div class=""><br class=""></div><div class="">I have the same reaction to these. Because indices are shared between collections and slices, instead of using a starting index, Swift's collection operations can just work on a slice. So instead of calling</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>let i = c.index(of: "A", from: firstIndex)</div><div class=""><br class=""></div><div class="">you can call</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>let i = c.suffix(from: firstIndex).index(of: "A”)</div></div></div></div></div></blockquote><div><br class=""></div><span style="font-size: 13px;" class="">The point is: The `i` above is an index into the (discarded) slice returned by `suffix()`, not the collection `c`. In general, it does not work correctly on the original collection. The behavior of slice indexes have changed a couple of times and is not totally consistent or guaranteed for different concrete collections. That is the reason I am proposing the above function to provide a sure way to have this functionality working properly and I find it extremely useful. Again I don’t know about others.</span></div><div><br class=""></div><div><span style="font-size: 13px;" class="">It seems that the subject of the interaction between slice indexes and the parent collections need further clarifications and specification from the core Swift team.</span><br style="font-size: 14px;" class=""><br class=""><blockquote type="cite" class=""><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div class=""><br class=""><blockquote type="cite" class=""><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div class=""><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">public</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">func</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">index</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""><C: Collection </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">where</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> ...</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">></span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">(of elementSequence: C) </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">-></span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> Index?</span></div><div class=""><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">public</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">func</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">index</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""><C: Collection </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">where</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> ...</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">></span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">(of elementSequence: C, </span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">from</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> </span><span class="pl-smi" style="box-sizing: border-box; color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">firstIndex</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">: Index</span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class="">) </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">-></span><span style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);" class=""> Index?</span></div></div></div></div></blockquote><div class=""><br class=""></div><div class="">These methods we <i class="">don't</i> have at all currently, and could really use! I would definitely support a proposal for finding a subsequence of a collection. There are several algorithms beyond the naive approach, so it would be interesting to see if / how a proposal could use those in a generic context.</div><div class=""><br class=""></div></div></div></div></div></blockquote><div style="font-size: 13px;"><br class=""></div><div style="font-size: 13px;">I updated <a href="https://gist.github.com/hooman/e77cc0e955a1db672ae49e45b0038d04" class="">the gist</a>. Besides some corrections and removing a couple of extension constraints, I merged the two functions above into:</div><div style="font-size: 13px;"><br class=""></div><div><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class=""><div class=""><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class=""><div class=""><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">public</span><span class="" style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);"> </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">func</span><span class="" style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);"> </span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">index</span><span class="" style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);"><C: Collection </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">where</span><span class="" style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);"> ...</span><span class="" style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);">></span><span class="" style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);">(of elementSequence: C, </span><span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">from</span><span class="" style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);"> </span><span class="pl-smi" style="box-sizing: border-box; color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">firstIndex</span><span class="" style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);">: Index? = </span><span style="color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;" class="">nil</span><span class="" style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);">) </span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">-></span><span class="" style="color: rgb(51, 51, 51); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre; background-color: rgb(255, 255, 255);"> Index?</span></div></div></div></div></div></div></div></div><div><br class=""></div><div style="font-size: 13px;">I think the basic implementation in the gist is good enough for many cases and we can specialize for array. As long as the collection and the sub-collection are not huge, performance should be fine.</div><div style="font-size: 13px;"><br class=""></div><div style="font-size: 13px;">On the other hand, I am too busy to seriously propose and pursue its addition. If enough people find it worthy of general inclusion into the standard library, somebody will pick it up, but not me.</div><div style="font-size: 13px;"><br class=""></div><div style="font-size: 13px;">I didn’t intend to hijack your proposal, but I thought some comments would help clarify things.</div><div style="font-size: 13px;"><br class=""></div><div style="font-size: 13px;">Thank you again,</div><div style="font-size: 13px;">Hooman</div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div class="">Thanks again!</div><div class="">Nate</div><div class=""><br class=""><blockquote type="cite" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div class=""><div class="">Look at the comments for the example usage. For `<span class="" style="color: rgb(121, 93, 163); font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; white-space: pre;">offset</span>` function, see the source code for usage.</div><div class=""><br class=""></div><div class="">Hooman</div><div class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On May 10, 2016, at 11:54 AM, Nate Cook via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><p style="-webkit-print-color-adjust: exact; margin: 15px 0px; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class="">I've needed these in the past and used them in other languages—any feedback on this idea?</p><div class=""><hr style="-webkit-print-color-adjust: exact; background-image: url(data:image/png;base64,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); background-color: rgb(255, 255, 255); border: 0px none; color: rgb(204, 204, 204); height: 4px; padding: 0px; font-family: Helvetica, arial, sans-serif; font-size: 14px; margin-top: 0px !important; background-position: 0px 0px; background-repeat: repeat no-repeat;" class=""><h1 id="toc_0" style="-webkit-print-color-adjust: exact; margin: 20px 0px 10px; padding: 0px; -webkit-font-smoothing: antialiased; cursor: text; position: relative; font-family: Helvetica, arial, sans-serif; background-color: rgb(255, 255, 255);" class="">Add <code style="-webkit-print-color-adjust: exact; margin: 0px 2px; padding: 0px 5px; white-space: nowrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">last(where:)</code> and <code style="-webkit-print-color-adjust: exact; margin: 0px 2px; padding: 0px 5px; white-space: nowrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">lastIndex(where:)</code> Methods to Bidirectional Collections</h1><p style="-webkit-print-color-adjust: exact; margin: 15px 0px; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class="">The standard library should include methods for finding the last element of a bidirectional collection that matches a predicate, along with the index of that element.</p><h2 id="toc_1" style="-webkit-print-color-adjust: exact; margin: 20px 0px 10px; padding: 0px; -webkit-font-smoothing: antialiased; cursor: text; position: relative; font-size: 24px; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(204, 204, 204); font-family: Helvetica, arial, sans-serif; background-color: rgb(255, 255, 255);" class="">Motivation</h2><p style="-webkit-print-color-adjust: exact; margin: 15px 0px; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class="">The standard library currently has (or will soon have) methods that perform a linear search from the beginning of a collection to find an element that matches a predicate:</p><div style="-webkit-print-color-adjust: exact; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class=""><pre class=" language-swift" style="-webkit-print-color-adjust: exact; margin-top: 0.5em; margin-bottom: 0.5em; background-color: rgb(245, 242, 240); border: 1px solid rgb(204, 204, 204); font-size: 13px; line-height: 1.5; overflow: auto; padding: 1em; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; text-shadow: white 0px 1px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; word-spacing: normal; word-break: normal; word-wrap: normal; tab-size: 4; -webkit-hyphens: none;"><code class=" language-swift" style="-webkit-print-color-adjust: exact; margin: 0px; padding: 0px; border: none; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-image: none; text-shadow: white 0px 1px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; tab-size: 4; -webkit-hyphens: none;"><span class="token keyword" style="-webkit-print-color-adjust: exact; color: rgb(0, 119, 170);">let</span> a <span class="token operator" style="-webkit-print-color-adjust: exact; color: rgb(166, 127, 89); background-color: rgba(255, 255, 255, 0.498039); background-position: initial initial; background-repeat: initial initial;">=</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">[</span><span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">20</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">,</span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">30</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">,</span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">10</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">,</span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">40</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">,</span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">20</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">,</span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">30</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">,</span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">10</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">,</span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">40</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">,</span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">20</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">]</span>
a<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">.</span><span class="token function" style="-webkit-print-color-adjust: exact; color: rgb(221, 74, 104);">first</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">(</span><span class="token keyword" style="-webkit-print-color-adjust: exact; color: rgb(0, 119, 170);">where</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">:</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">{</span> $<span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">0</span> <span class="token operator" style="-webkit-print-color-adjust: exact; color: rgb(166, 127, 89); background-color: rgba(255, 255, 255, 0.498039); background-position: initial initial; background-repeat: initial initial;">></span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">25</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">}</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">)</span> <span class="token comment" spellcheck="true" style="-webkit-print-color-adjust: exact; color: rgb(112, 128, 144);">// 30</span>
a<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">.</span><span class="token function" style="-webkit-print-color-adjust: exact; color: rgb(221, 74, 104);">index</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">(</span>of<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">:</span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">10</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">)</span> <span class="token comment" spellcheck="true" style="-webkit-print-color-adjust: exact; color: rgb(112, 128, 144);">// 2</span>
a<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">.</span><span class="token function" style="-webkit-print-color-adjust: exact; color: rgb(221, 74, 104);">index</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">(</span><span class="token keyword" style="-webkit-print-color-adjust: exact; color: rgb(0, 119, 170);">where</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">:</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">{</span> $<span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">0</span> <span class="token operator" style="-webkit-print-color-adjust: exact; color: rgb(166, 127, 89); background-color: rgba(255, 255, 255, 0.498039); background-position: initial initial; background-repeat: initial initial;">></span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">25</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">}</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">)</span> <span class="token comment" spellcheck="true" style="-webkit-print-color-adjust: exact; color: rgb(112, 128, 144);">// 1</span></code></pre></div><p style="-webkit-print-color-adjust: exact; margin: 15px 0px; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class="">Unfortunately, there is no such method that searches from the end of a bidirectional collection. Finding the last of particular kind of element has multiple applications, particularly with text, such as wrapping a long string into lines of a maximum length or trimming whitespace from the beginning and end of a string.</p><p style="-webkit-print-color-adjust: exact; margin: 15px 0px; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class="">This limitation can be worked around by using the methods above on the reversed collection, but the resulting code is truly dreadful. For example, to find the corresponding last index to <code style="-webkit-print-color-adjust: exact; margin: 0px 2px; padding: 0px 5px; white-space: nowrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">a.index(where: { $0 > 25 })</code>, this unholy incantation is required:</p><div style="-webkit-print-color-adjust: exact; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class=""><pre class=" language-swift" style="-webkit-print-color-adjust: exact; margin-top: 0.5em; margin-bottom: 0.5em; background-color: rgb(245, 242, 240); border: 1px solid rgb(204, 204, 204); font-size: 13px; line-height: 1.5; overflow: auto; padding: 1em; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; text-shadow: white 0px 1px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; word-spacing: normal; word-break: normal; word-wrap: normal; tab-size: 4; -webkit-hyphens: none;"><code class=" language-swift" style="-webkit-print-color-adjust: exact; margin: 0px; padding: 0px; border: none; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-image: none; text-shadow: white 0px 1px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; tab-size: 4; -webkit-hyphens: none;"><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">(</span>a<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">.</span><span class="token function" style="-webkit-print-color-adjust: exact; color: rgb(221, 74, 104);">reversed</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">(</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">)</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">.</span><span class="token function" style="-webkit-print-color-adjust: exact; color: rgb(221, 74, 104);">index</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">(</span><span class="token keyword" style="-webkit-print-color-adjust: exact; color: rgb(0, 119, 170);">where</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">:</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">{</span> $<span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">0</span> <span class="token operator" style="-webkit-print-color-adjust: exact; color: rgb(166, 127, 89); background-color: rgba(255, 255, 255, 0.498039); background-position: initial initial; background-repeat: initial initial;">></span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">25</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">}</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">)</span><span class="token operator" style="-webkit-print-color-adjust: exact; color: rgb(166, 127, 89); background-color: rgba(255, 255, 255, 0.498039); background-position: initial initial; background-repeat: initial initial;">?</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">.</span>base<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">)</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">.</span><span class="token function" style="-webkit-print-color-adjust: exact; color: rgb(221, 74, 104);">flatMap</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">(</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">{</span> a<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">.</span><span class="token function" style="-webkit-print-color-adjust: exact; color: rgb(221, 74, 104);">index</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">(</span>before<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">:</span> $<span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">0</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">)</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">}</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">)</span></code></pre></div><p style="-webkit-print-color-adjust: exact; margin: 15px 0px; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class="">Wat.</p><h2 id="toc_2" style="-webkit-print-color-adjust: exact; margin: 20px 0px 10px; padding: 0px; -webkit-font-smoothing: antialiased; cursor: text; position: relative; font-size: 24px; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(204, 204, 204); font-family: Helvetica, arial, sans-serif; background-color: rgb(255, 255, 255);" class="">Proposed solution</h2><p style="-webkit-print-color-adjust: exact; margin: 15px 0px; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class="">Bidirectional collections should include three new methods for symmetry with the existing forward-searching APIs: <code style="-webkit-print-color-adjust: exact; margin: 0px 2px; padding: 0px 5px; white-space: nowrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">last(where:)</code>, <code style="-webkit-print-color-adjust: exact; margin: 0px 2px; padding: 0px 5px; white-space: nowrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">lastIndex(where:)</code>, and <code style="-webkit-print-color-adjust: exact; margin: 0px 2px; padding: 0px 5px; white-space: nowrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">lastIndex(of:)</code>, specifically for collections of <code style="-webkit-print-color-adjust: exact; margin: 0px 2px; padding: 0px 5px; white-space: nowrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">Equatable</code> elements.</p><p style="-webkit-print-color-adjust: exact; margin: 15px 0px; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class="">These additions would remove the need for searching in a reversed collection and allow code like the following:</p><div style="-webkit-print-color-adjust: exact; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class=""><pre class=" language-swift" style="-webkit-print-color-adjust: exact; margin-top: 0.5em; margin-bottom: 0.5em; background-color: rgb(245, 242, 240); border: 1px solid rgb(204, 204, 204); font-size: 13px; line-height: 1.5; overflow: auto; padding: 1em; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; text-shadow: white 0px 1px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; word-spacing: normal; word-break: normal; word-wrap: normal; tab-size: 4; -webkit-hyphens: none;"><code class=" language-swift" style="-webkit-print-color-adjust: exact; margin: 0px; padding: 0px; border: none; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-image: none; text-shadow: white 0px 1px; font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace; word-spacing: normal; word-break: normal; word-wrap: normal; line-height: 1.5; tab-size: 4; -webkit-hyphens: none;">a<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">.</span><span class="token function" style="-webkit-print-color-adjust: exact; color: rgb(221, 74, 104);">last</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">(</span><span class="token keyword" style="-webkit-print-color-adjust: exact; color: rgb(0, 119, 170);">where</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">:</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">{</span> $<span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">0</span> <span class="token operator" style="-webkit-print-color-adjust: exact; color: rgb(166, 127, 89); background-color: rgba(255, 255, 255, 0.498039); background-position: initial initial; background-repeat: initial initial;">></span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">25</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">}</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">)</span> <span class="token comment" spellcheck="true" style="-webkit-print-color-adjust: exact; color: rgb(112, 128, 144);">// 40</span>
a<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">.</span><span class="token function" style="-webkit-print-color-adjust: exact; color: rgb(221, 74, 104);">lastIndex</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">(</span>of<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">:</span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">10</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">)</span> <span class="token comment" spellcheck="true" style="-webkit-print-color-adjust: exact; color: rgb(112, 128, 144);">// 6</span>
a<span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">.</span><span class="token function" style="-webkit-print-color-adjust: exact; color: rgb(221, 74, 104);">lastIndex</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">(</span><span class="token keyword" style="-webkit-print-color-adjust: exact; color: rgb(0, 119, 170);">where</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">:</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">{</span> $<span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">0</span> <span class="token operator" style="-webkit-print-color-adjust: exact; color: rgb(166, 127, 89); background-color: rgba(255, 255, 255, 0.498039); background-position: initial initial; background-repeat: initial initial;">></span> <span class="token number" style="-webkit-print-color-adjust: exact; color: rgb(153, 0, 85);">25</span> <span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">}</span><span class="token punctuation" style="-webkit-print-color-adjust: exact; color: rgb(153, 153, 153);">)</span> <span class="token comment" spellcheck="true" style="-webkit-print-color-adjust: exact; color: rgb(112, 128, 144);">// 7</span></code></pre></div><p style="-webkit-print-color-adjust: exact; margin: 15px 0px; font-family: Helvetica, arial, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);" class="">Much better!</p></div></div>_______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a><br class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class=""></div></blockquote></div><br class=""></div></div></div></div></blockquote></div><br class=""></div></div></div></blockquote></div><br class=""></div></div></body></html>