<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=""><blockquote type="cite" class="">On Apr 22, 2016, at 11:29 AM, David Sweeris <<a href="mailto:davesweeris@mac.com" class="">davesweeris@mac.com</a>> wrote:<br class=""></blockquote><div><blockquote type="cite" class=""><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=""><blockquote type="cite" class="">On Apr 22, 2016, at 9:56 AM, Stephen Canon via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</blockquote><div class=""><blockquote type="cite" class=""><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=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Apr 22, 2016, at 10:54 AM, Xiaodi Wu <<a href="mailto:xiaodi.wu@gmail.com" class="">xiaodi.wu@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: 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="">Naive question: is it necessary to make a trade-off here? Why not an</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: 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-caps: 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="">associated type Exponent that's Int for Float, Double, and Float80,</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: 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-caps: 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="">allowing for something else for bignums?</span></div></blockquote></div><br class=""><div class="">It’s an added (fairly minor) complexity to the API surface that confers approximately zero benefit.</div></div></div></blockquote><br class=""></div><div class="">So you admit the benefit isn’t *actually* zero? :-)<div class=""><br class=""></div><div class="">Yes, it does add a small bit of complexity to the API’s surface, but it's on a part of the surface that I don’t think people look at very much. How often are people extracting a float’s exponent? Plus, I suspect there’s a fair bit of overlap between the group of people who even know what `.exponent` would get used for, and those who’d get a warm fuzzy feeling from seeing that the standard library has baked-in, low-level support for bignum / arbitrary precision types.</div><div class=""><br class=""></div><div class="">Embrace the warm fuzzies… make exponent be an associated type.</div><div class=""><br class=""></div><div class="">- Dave Sweeris (who, despite the light-hearted tone, thinks this is actually pretty important)</div></div></div></div></blockquote><br class=""></div><div>The current design does not prevent bignum / arbitrary precision types. It prevents soft-float types with ridiculously large exponent ranges, but such enormous numbers are generally better modeled by either a logarithmic number system or level-index arithmetic.</div><div><br class=""></div><div>Making exponent an associated type makes implementing any future heterogeneous operations (including generic conversions) more complex. This is a real cost, for a dubious theoretical benefit.</div><div><br class=""></div><div>– Steve</div></body></html>