<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=""><div class="">Anything where you *specify* angles benefits from a rational type (e.g. representing fractions-of-π) that gets converted to floating-point only when necessary (e.g. to use trig functions).</div><div class=""><br class=""></div><div><blockquote type="cite" class=""><div class="">On Dec 7, 2015, at 8:11 AM, Stephen Canon 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=""><div class="" 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;">Can you guys specify some of the use cases that you have in mind for a Rational type? You mention "alleviating the pain points of floating-point math,” but rationals tend to be used *very* differently from floating-point types in computation.</div><div class="" 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;"><br class=""></div><div class="" 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;">Thanks,</div><div class="" 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;">– Steve</div><br class="" 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;"><div 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=""><div class="">On Dec 7, 2015, at 5:44 AM, Davide De Franceschi 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=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">While I agree that a Rational type, one that would preserve quotient and denominator info, would be very nice, I think that it's more fit for a Math framework.<div class="">If we're just talking about a type that holds precise decimal info, I think making NSDecimal (planned to be renamed as Decimal in the future) usable is what we should do.</div><div class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On 7 Dec 2015, at 10:28, T.J. Usiyan 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=""><div dir="ltr" class="">I'm all for a stdlib Rational Type. I've written one as well and would be glad not to have to include it as a dependency everywhere.<div class="">TJ</div></div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Mon, Dec 7, 2015 at 1:31 PM, Harlan Haskins via swift-evolution<span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:swift-evolution@swift.org" target="_blank" class="">swift-evolution@swift.org</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"><div class="" style="word-wrap: break-word;">If Swift 3 is going to focus on re-thinking the Numerics in the system, it might be worth considering adding a Fraction (or Rational) type to the standard library. This, coupled with an arbitrary-precision integer type, would be a great way to handle arbitrary-precision decimal arithmetic, and can alleviate almost all the pain points of floating-point math.<div class=""><br class=""></div><div class="">There exist now some really nice implementations of Fractions, but the ones I’ve seen haven’t been implemented fully generically.</div><div class="">My favorite is this one:<span class="Apple-converted-space"> </span><a href="https://gist.github.com/JadenGeller/5e80ebf32442acc62e8e" target="_blank" class="">https://gist.github.com/JadenGeller/5e80ebf32442acc62e8e</a></div><div class=""><br class=""></div><div class="">I’d love to see some standard library support with rock-solid, fast implementations of all the common algorithms (GCD, LCD, LCM, reduction, etc) and good conformance to the builtin integer protocols. Maybe even<span class="Apple-converted-space"> </span><font face="Menlo" class="">FloatLiteralConvertible</font>, too, with some logic for converting rational floats.</div><div class=""><br class=""></div><div class="">Thoughts?</div><div class=""><br class=""></div><div class="">- Harlan Haskins</div><img src="https://u2002410.ct.sendgrid.net/wf/open?upn=3FGfocPbgxkNkmje7djckg9Iw-2BGYY3X6RxJ1tkUXKCr1mGWLtle38JhdUCkzNvAFKca8BI2IZiTedPLguLDg1TtEYLXGYWH-2BewJkLb-2BjDBcqBgL2BYa-2Bl3NtT5XEQq3q0-2BrFJrSHllGvw98ZC-2Fu4xrlfCCw4-2BsieLIEsY7P-2BUNjLXPzadS22jPmYlmgrNHQz8IRukh5taYbBZlJSrd3mryYE4ngwTngf508M5-2BYT-2Bk8-3D" alt="" width="1" height="1" border="0" class="" style="min-height: 1px !important; width: 1px !important; border-width: 0px !important; margin: 0px !important; padding: 0px !important;"></div></blockquote></div></div></div></blockquote></div></div></div></div></blockquote></div><br class="" 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;"><img src="https://u2002410.ct.sendgrid.net/wf/open?upn=9EwXyNl81W9TT3yZ17PL28-2Be7Ks-2FXLjqa0dZcsddi5bylGn9X-2BJ77ZhHzc04hbvNA2RmtB4FCykviCpxHmdb3k4-2BTWsQUxF-2BDCts2v4BYDYGZjm4ozY-2Bq81LAlLl-2F-2FhgFq6jxCfEVFvN1zIG285hz3tzHG21nWu7zmYK62wtWShJXY65ZelWSTR4ig5Cj-2BY-2F7HhH6Xat0oE5T14iSu9SG9Fu3su-2BsXZcKJf-2FGVcLy7M-3D" alt="" width="1" height="1" border="0" 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; height: 1px !important; width: 1px !important; border-width: 0px !important; margin: 0px !important; padding: 0px !important;" 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=""><span class="Apple-converted-space"> </span></span><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="">_______________________________________________</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="">swift-evolution mailing list</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=""><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><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=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" 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="">https://lists.swift.org/mailman/listinfo/swift-evolution</a></div></blockquote></div><br class=""></body></html>