<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=""><br class=""><div><blockquote type="cite" class=""><div class="">On Jan 16, 2017, at 9:43 AM, Charles Srstka via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div></blockquote></div><div><blockquote type="cite" class=""><b class="">I don’t even know how long it actually takes to finish this test, because the last time I did this I eventually got sick of waiting and killed the process. So, I don’t know quite how many orders of magnitude slower it is, but it’s a lot.</b></blockquote><br class=""></div><div>That’s all the endorsement I need. +1 from me.</div><div><br class=""></div><div><br class=""></div><div>I do wonder if there is any way to get this sort of optimization out of the compiler. I suppose it would be difficult because the compiler doesn’t know what the mutable vs immutable pairs are or if such a pair even exists (array doesn’t have appending()).</div><div><br class=""></div><div>If we assume + for Array had a mutating variant ala func + (lhs: inout Array, rhs: Array) { … }, would the compiler be able to prefer the inout version? What if a type wanted to offer a specialized version of a function for the compiler to call when the compiler can prove only temporaries are involved? I don’t want to go too far down the road of move constructors and whatnot for that way lies madness.</div><div><br class=""></div><div><br class=""></div><div>(Not a compiler expert, just wondering if there is a way to make situations like this into a “pit of success”).</div><div><br class=""></div><div>Russ</div></body></html>