<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 Jun 2, 2017, at 10:26 AM, 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-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: Helvetica; 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="">on Fri Jun 02 2017, Brent Royal-Gordon <</span><a href="mailto:swift-evolution@swift.org" 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-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">swift-evolution@swift.org</a><span style="font-family: Helvetica; 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="">> wrote:</span><br style="font-family: Helvetica; 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=""><br style="font-family: Helvetica; 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=""><blockquote type="cite" 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-size-adjust: auto; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" class="">On May 28, 2017, at 11:37 PM, Daryle Walker via swift-evolution<br class=""><<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class="">Static-Sized Arrays<br class=""></blockquote><br class="">My preference would still be to build this from four separate features:<br class=""><br class="">1. Magic tuple conformances: We already want to be able to<br class="">automatically conform tuples to protocols like Equatable, Hashable,<br class="">and Comparable. These can all be compiler magic; they don't have to be<br class="">definable in userspace.<br class=""><br class="">2. Conform tuples to Collection: The Element type should be the most<br class="">specific common supertype of the tuple's elements. If all the elements<br class="">are the same type, it would be that type. The Index and IndexDistance<br class="">types should be Int.<br class=""><br class="">3. Conform same-type tuples to MutableCollection: If all elements are<br class="">the same type, you can also modify the values. (If their types vary in<br class="">any way, however, it would not be safe to allow mutations, since you<br class="">could assign the wrong type to an element.)<br class=""><br class="">3. Add sugar for a tuple of N identical elements: Probably something<br class="">like `4 * Int`, but opinions can vary.</blockquote></div></blockquote><div><br class=""></div><div>Static-sized arrays should not be shoved into being a tuple with funny settings; that introduces subtleties into the tuple concept only because of jammed-in array support. The fact 3 separate-proposal-worthy features need to be introduced first, in which at least one is dubious in value (#2, since a lot of times the common type would be “Any”), should be a code smell on this approach.</div><div><br class=""></div><blockquote type="cite" class=""><div class=""><span style="font-family: Helvetica; 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="">I think any complete solution depends on at least two more things:</span><br style="font-family: Helvetica; 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=""><br style="font-family: Helvetica; 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: Helvetica; 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="">1. adding the ability to get an UnsafePointer to an immutable instance</span><br style="font-family: Helvetica; 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: Helvetica; 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=""> of value type</span><br style="font-family: Helvetica; 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></blockquote><div><br class=""></div><div>Do you mean something besides applying the address-of operator (I’m not sure what that is.) to “myArray.0”?</div><div><br class=""></div><div>What are you thinking of doing with such unsafe-pointers? In this thread, I had “array of T” or “[of T]” to make array-segment references, so you can make a function that can take an array of a certain type without specializing for each shape. (Worse, since we only have type-based generic parameters, we couldn’t generate such functions.) It’s the same as using “T[]” as a function parameter type in C.</div><div><br class=""></div><div>While thinking of this response, I looked at the same section of <a href="http://SwiftDoc.org" class="">SwiftDoc.org</a> for UnsafePointer, and there were Unsafe(Mutable)BufferPointer. These types do the same job as my theoretical “[of T]”, so maybe I should defer to those. We would add a global function to convert given arrays to unsafe-buffer-pointers.</div><div><br class=""></div><blockquote type="cite" class=""><div class=""><span style="font-family: Helvetica; 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="">2. support for leaving some of the elements uninitialized, or</span><br style="font-family: Helvetica; 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: Helvetica; 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=""> alternatively, a variation of this type that is RangeReplaceable but</span><br style="font-family: Helvetica; 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: Helvetica; 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=""> also bounded in capacity.</span><br style="font-family: Helvetica; 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></blockquote></div><br class=""><div class="">AFAIK, all objects have to be fully initialized before the first read. If that’s the case, then skipping element initialization (which I can understand wanting when using a large array for a mathematical matrix type) would require a separate proposal, since we would need a full consideration of the consequences. (What happens when reading an uninitialized element?) For the variant, couldn’t that be implemented with a library type (since you need a per-object list of current elements), maybe using the base array type as a generic parameter.</div><div class=""><br class="webkit-block-placeholder"></div><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">— </div><div class="">Daryle Walker<br class="">Mac, Internet, and Video Game Junkie<br class="">darylew AT mac DOT com </div><div class=""><br class=""></div></div></div></body></html>