<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 21 Feb 2017, at 21:39, Max Moiseev <<a href="mailto:moiseev@apple.com" class="">moiseev@apple.com</a>> wrote:</div><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=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Feb 18, 2017, at 12:02 PM, Karl Wagner 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=""><span style="font-family: Helvetica; font-size: 14px; 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="">I assume the “SignedNumber” protocol is the same as the existing one in the standard library. That is to say, Strideable.Stride will now conform to Number and have operators.</span><br style="font-family: Helvetica; font-size: 14px; 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=""></div></blockquote>SignedNumber will *not* be the same. It is just the same name.</div><div class="">Stride will have operators, yes. Strideable in general will not, unless it’s a _Pointer. (you can find the current implementation prototype <a href="https://github.com/apple/swift/blob/new-integer-protocols/stdlib/public/core/Stride.swift.gyb" class="">here</a>).<br class=""></div></div></div></blockquote><div><br class=""></div><div>Currently, it’s difficult to work with Strideable because you can calculate distances between them (as type Strideable.Stride), but you can’t add those distances because Strideable.Stride is only constrained to conform to “SignedNumber”, which is a pretty useless protocol.</div><div><br class=""></div><div>In the prototype, Strideable.Stride has now been changed, so it is constrained to “SignedArithmetic” (which, apparently, is to be renamed “SignedNumber”). So essentially, the existing SignedNumber has been re-parented to “Number” and gains operations such as addition. That’s great!</div><div><br class=""></div><div>I think it would be worth including Strideable in the “big picture” in the proposal/manifesto, showing how it fits in..</div><br class=""><blockquote type="cite" class=""><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><blockquote type="cite" class=""><div class=""><br style="font-family: Helvetica; font-size: 14px; 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: 14px; 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="">Also minor nitpick, would it be too onerous to require Number.Magnitude to be Comparable? Currently it’s only Equatable and ExpressibleByIntegerLiteral.</span></div></blockquote>Magnitude is supposed to conform to Arithmetic (or Number, or whatever it ends up being called), but the recursive constraints feature is missing, therefore we constrained it with the protocols that Arithmetic itself refines.</div><div class=""><br class=""></div><div class="">Why would you want Comparable?</div><div class=""><br class=""></div><div class="">Max</div><br class=""></div></div></blockquote></div><br class=""><div class="">I suppose that leads me on to the question of why Number itself only requires that conformers be (Equatable & ExpressibleByIntegerLiteral) and does not require that they be Comparable.</div><div class=""><br class=""></div><div class="">If I must be able to create any “Number" out of thin air with an integer literal, is it not reasonable to also require that I am able to compare two instances?</div><div class=""><br class=""></div><div class="">Are there Number types which can’t be Comparable?</div><div class=""><br class=""></div><div class="">- Karl</div></body></html>