<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div class="">
<div style="color: rgb(0, 0, 0); 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; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Saagar Jha</div>
</div>
<div><br class=""><blockquote type="cite" class=""><div class="">On Jan 17, 2018, at 16:56, Xiaodi Wu 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" style="font-family: SFProText-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">On Wed, Jan 17, 2018 at 2:04 AM, David Sweeris<span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:davesweeris@mac.com" target="_blank" class="">davesweeris@mac.com</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-style: solid; border-left-color: rgb(204, 204, 204); padding-left: 1ex;"><br class=""><br class="">Sent from my iPhone<br class=""><span class=""><br class="">> On Jan 16, 2018, at 23:45, Jonathan Hull via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class="">><br class="">> Mainly semantics.<br class="">><br class="">> We could technically use Int instead of having a Bool type (just using 1 and 0). We don’t do that since Int and Bool have intrinsically different meanings in code.<br class="">><br class="">> What I am saying is that parameters that take the range 0 to 1 typically have a fundamentally different meaning (or at least a different way of thinking about them) than Doubles. It would be nice to be able to see that distinction when using APIs.<br class="">><br class="">> With both this and the Angle type, I am pointing out areas where, due to historical reasons in C, we have conflated a bunch of types which have different behavior, and then just expect programmers to be conscientious enough to use them correctly in each case. These types/numbers all have a different forms of dimensionality.<br class="">><br class="">> I’d like to discuss that before we lock everything down.<br class=""><br class=""></span>+1 (although I think a “normalized to [0, 1]” type would be more useful than a “percentage” type)<br class=""></blockquote><div class=""><br class=""></div><div class="">Bool is not a good example; it permits precisely two logical values (0 and 1). By contrast, if you're going to support 1000%, then your type supports the same values as the underlying storage. As I wrote in a different thread, one way to look at a type is the set of values that a variable can have.</div><div class=""><br class=""></div><div class="">What is your limiting principle here if you think that a range that's not enforced makes a value become of a different type? Often, a 1-5 rating system is used. Sometimes, it's 1-4 or 1-10. And of course, a "3" on a 1-5 scale means something very different from a "3" on a 1-10 scale. Should ScaleFrom1To5 be its own type? And also ScaleFrom1To4 and ScaleFrom1To10?</div></div></div></div></div></blockquote><div><br class=""></div><div>Just a thought: if Swift ever allows integer literals in generics (e.g. for a fixed size array equivalent to C++’s std::array), this seems like how a type like ScaleFrom (and a percent type, for that matter) could be implemented.</div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" style="font-family: SFProText-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><div class="gmail_extra"><div class="gmail_quote"><div class=""><br class=""></div><div class="">Besides, even supposing a percentage type would be in high demand, there's no need for its inclusion in the standard library. It's very easy to implement on your own in a third-party library. Moreover, custom operators will allow you to define a postfix `%`, and then you could write: `let x = 100%`. Throw in some heterogeneous arithmetic operators and you could do almost any math you want.</div></div></div></div><span style="font-family: SFProText-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">_______________________________________________</span><br style="font-family: SFProText-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: SFProText-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">swift-evolution mailing list</span><br style="font-family: SFProText-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><a href="mailto:swift-evolution@swift.org" style="font-family: SFProText-Regular; 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-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">swift-evolution@swift.org</a><br style="font-family: SFProText-Regular; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" style="font-family: SFProText-Regular; 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-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a></div></blockquote></div><br class=""></body></html>