<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="">Is it a requirement that collections share indices with its subsequence? Array and ArraySlice do share indices, which is why ArraySlice isn’t zero-based, and I think this is convenient. But String.CharacterView doesn’t seem to share indices with its subsequence (which is String.CharacterView as well). Consider this example:<div class=""><br class=""></div><div class=""><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="">let</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> foo = </span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">"foobar"</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">.</span><span style="font-variant-ligatures: no-common-ligatures" class="">characters</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""></span><br class=""></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">let</span><span style="font-variant-ligatures: no-common-ligatures" class=""> index = </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">foo</span><span style="font-variant-ligatures: no-common-ligatures" class="">.</span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">index</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">foo</span><span style="font-variant-ligatures: no-common-ligatures" class="">.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">startIndex</span><span style="font-variant-ligatures: no-common-ligatures" class="">, offsetBy: </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">3</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;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">let</span><span style="font-variant-ligatures: no-common-ligatures" class=""> bar = </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">foo</span><span style="font-variant-ligatures: no-common-ligatures" class="">.</span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">suffix</span><span style="font-variant-ligatures: no-common-ligatures" class="">(from: </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">index</span><span style="font-variant-ligatures: no-common-ligatures" class="">) </span><span style="font-variant-ligatures: no-common-ligatures; color: #008400" class="">// "bar"</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""></span><br class=""></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">foo</span><span style="font-variant-ligatures: no-common-ligatures" class="">[</span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">index</span><span style="font-variant-ligatures: no-common-ligatures" class="">] </span><span style="font-variant-ligatures: no-common-ligatures; color: #008400" class="">// "b" :)</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: #4f8187" class="">foo</span><span style="font-variant-ligatures: no-common-ligatures" class="">[</span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">bar</span><span style="font-variant-ligatures: no-common-ligatures" class="">.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">startIndex</span><span style="font-variant-ligatures: no-common-ligatures" class="">] </span><span style="font-variant-ligatures: no-common-ligatures; color: #008400" class="">// "f" :(</span></div></div><div class=""><br class=""></div><div class="">So does this mean that we can’t assume that collections and their subsequences share their indices (which could be very handy), or is this just a bug related to String.CharacterView?</div></body></html>