<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">The lines just after the current declaration show the desired version, which is waiting on two generics features that are in the pipeline:<div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp;&nbsp;</span><span style="font-variant-ligatures: no-common-ligatures" class="">// FIXME(ABI)#98 (Recursive Protocol Constraints):</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">// FIXME(ABI)#99 (Associated Types with where clauses):</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">// associatedtype SubSequence : Collection</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">// &nbsp; where</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">// &nbsp; Iterator.Element == SubSequence.Iterator.Element,</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">// &nbsp; SubSequence.Index == Index,</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">// &nbsp; SubSequence.Indices == Indices,</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">// &nbsp; SubSequence.SubSequence == SubSequence</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">//</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">// (&lt;<a href="rdar://problem/20715009" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #1337ff" class="">rdar://problem/20715009</span></a>&gt; Implement recursive protocol</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">// constraints)</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">//</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">// These constraints allow processing collections in generic code by</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">&nbsp; </span><span style="font-variant-ligatures: no-common-ligatures" class="">// repeatedly slicing them in a loop.</span></div><div class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div><div class=""><span style="font-variant-ligatures: no-common-ligatures" class="">Huon</span></div><div class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div><div><blockquote type="cite" class=""><div class="">On Feb 13, 2017, at 13:42, Charles Srstka via swift-evolution &lt;<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>&gt; wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=us-ascii" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">The following comment accompanies the declaration of the SubSequence associated type in the Collection protocol:</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/// A sequence that represents a contiguous subrange of the collection's</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/// elements.</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #008400" class="">///</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/// This associated type appears as a requirement in the `Sequence`</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/// protocol, but it is restated here with stricter constraints. In a</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/// collection, the subsequence should also conform to `Collection`.</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(112, 61, 170);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">associatedtype</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> SubSequence : </span><span style="font-variant-ligatures: no-common-ligatures" class="">IndexableBase</span><span style="font-variant-ligatures: no-common-ligatures;" class="">, </span><span style="font-variant-ligatures: no-common-ligatures" class="">Sequence</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> = </span><span style="font-variant-ligatures: no-common-ligatures" class="">Slice</span><span style="font-variant-ligatures: no-common-ligatures;" class="">&lt;</span><span style="font-variant-ligatures: no-common-ligatures" class="">Self</span><span style="font-variant-ligatures: no-common-ligatures;" class="">&gt;</span></div></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(112, 61, 170);" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""><br class=""></span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(112, 61, 170);" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""><span style="font-family: Helvetica; font-size: 12px;" class="">The comments clearly state that the subsequence should conform to Collection, however, it is not declared as such. Why is this?</span></span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(112, 61, 170);" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""><span style="font-family: Helvetica; font-size: 12px;" class=""><br class=""></span></span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(112, 61, 170);" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""><span style="font-family: Helvetica; font-size: 12px;" class="">Charles</span></span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(112, 61, 170);" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""><span style="font-family: Helvetica; font-size: 12px;" class=""><br class=""></span></span></div></div>__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