<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 May 6, 2016, at 8:15 PM, Dave Abrahams 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=""><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">on Fri May 06 2016, Matthew Johnson <</span><a href="mailto:swift-evolution@swift.org" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">swift-evolution@swift.org</a><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">> wrote:</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" class="">On May 6, 2016, at 7:30 PM, Dave Abrahams via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class=""><br class="">on Fri May 06 2016, Cole Campbell <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class=""><blockquote type="cite" class="">I don't know if it's considered too late at this point to rename 'reduce', but<br class="">I'll add an enthusiastic +1 to renaming it to 'fold' and adding 'unfold'. 'Fold'<br class="">is just as obvious a name as 'reduce', IMO (actually I even prefer<br class="">it).<span class="Apple-converted-space"> </span><br class=""></blockquote><br class="">It's not, IMO. “Reduce” was chosen deliberately over “fold” because we<br class="">think it is more in “common currency” among programmers, in no small<br class="">part to the notice that MapReduce has gotten.<br class=""></blockquote><br class="">I was guessing this was the rationale. But if it’s not too late and<br class="">“fold” solves the “unfold” naming problem maybe we that balances out<br class="">the equation.<br class=""></blockquote><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">Personally, I'm not confident “unfold” would be considered to meet the</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">utility bar, even if we changed the name of “reduce,” FWIW.</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">Which name do you think best communicates the essence of the<br class="">operation? IMO “fold” does a much better job of this.<br class=""></blockquote><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">Personally I think “accumulate” does that better than either name, but</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">it doesn't matter. What matters, IMO, is what more people will be</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">familiar with.</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""></div></blockquote><div><br class=""></div>Fair enough.</div><div><br class=""></div><div>FWIW, the reason I like fold is that it helps me to visualize the process mentally.</div><div><br class=""><blockquote type="cite" class=""><div class=""><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""><br class=""><blockquote type="cite" class=""><br class=""><blockquote type="cite" class="">I think changing it now with other source-breaking changes is better<br class="">than moving forward with 'reduce' and a corresponding function with a<br class="">confusing name. Fold/unfold would fit in beautifully with the<br class="">prefix/suffix pairings already in the standard library.<br class=""><br class="">Cole<br class=""><br class="">On May 6, 2016, at 1:29 AM, David Hart via swift-evolution<br class=""><<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class=""> If we are discussing naming changes to reduce, here's my personal opinion:<br class=""><br class=""> * When I first encountered it, I understood exactly what it did because I<br class=""> knew that term of art. If it was named sequence, I would have been confused.<br class=""> * If we are discussing name changes, I'd personally vote to change it to<br class=""> fold. It is the other term of art used for it, and it makes unfold work.<br class=""><br class=""> David<br class=""><br class=""> On 05 May 2016, at 22:39, Chris Lattner via swift-evolution<br class=""> <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class=""> On May 5, 2016, at 1:03 PM, Erica Sadun <<a href="mailto:erica@ericasadun.com" class="">erica@ericasadun.com</a>><br class=""> wrote:<br class=""><br class=""> On May 4, 2016, at 5:50 PM, Chris Lattner via swift-evolution<br class=""> <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class=""> Proposal link:<br class=""> <a href="https://github.com/apple/swift-evolution/blob/master/proposals/0045-scan-takewhile-dropwhile.md" class="">https://github.com/apple/swift-evolution/blob/master/proposals/0045-scan-takewhile-dropwhile.md</a><br class=""><br class=""> Sequence.prefix(while:) & Sequence.drop(while:) - These are<br class=""> *accepted* as specified in revision 3 of the proposal.<br class=""><br class=""> I'm still a little sad we didn't go for `prefix`/`suffix` or `take`/<br class=""> `drop` pairs that linguistically matched.Nonetheless I'm gratified<br class=""> these are hopping into the language. That said, I'm going to put on<br class=""> my painters cap to consider selecting some exterior latex for the<br class=""> feature I was most looking forward to in this proposal:<br class=""><br class=""> Core team writes:<br class=""><br class=""> unfold(_:applying:) - This addition is *rejected* by the core<br class=""> team as written, but deserves more discussion in the community,<br class=""> and potentially could be the subject of a future proposal. The<br class=""> core team felt that the utility of this operation is high enough<br class=""> to be worth including in the standard library, but could not<br class=""> find an acceptable name for it. “unfold” is problematic, despite<br class=""> its precedence in other language, because Swift calls the<br class=""> corresponding operation “reduce” and not “fold”. No one could<br class=""> get excited about “unreduce”. “iterate” was also considered, but<br class=""> a noun is more appropriate than an verb in this case. Given the<br class=""> lack of a good name, the core team preferred to reject to let<br class=""> the community discuss it more.<br class=""><br class=""> A few thoughts:<br class=""><br class=""> * I'm not sure why a noun is more appropriate than a verb. Reduce<br class=""> isn't a noun, prefix isn't a noun, drop isn't a noun.<span class="Apple-converted-space"> </span><br class=""><br class=""> I’m not a naming guru, but my understanding is that ‘reduce’ was picked<br class=""> because it was term of art (like map), which is what allowed the misuse<br class=""> of a verb.<br class=""><br class=""> One idea that came out of the core team discussion was something like:<br class=""><br class=""> sequence(from: 0) { $0 += 42 }<br class=""><br class=""> Since it returns a sequence.<br class=""><br class=""> -Chris<br class=""><br class=""> _______________________________________________<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=""><br class=""> _______________________________________________<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=""><br class="">_______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a><br class="">https://lists.swift.org/mailman/listinfo/swift-evolution<br class=""></blockquote><br class="">--<span class="Apple-converted-space"> </span><br class="">Dave<br class=""><br class="">_______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a><br class="">https://lists.swift.org/mailman/listinfo/swift-evolution<br class=""></blockquote><br class="">_______________________________________________<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=""></blockquote><br style="font-family: Helvetica; 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