<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="">This is not possible in Swift 3.0. Swift 4.0 will improve things with conditional conformances.<div class=""><br class=""></div><div class="">For now, the best solution is using global functions instead of extending types or protocols.</div><div class=""><br class=""></div><div class="">For example you can do this now:</div><div class=""><br class=""></div><div class=""><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="">extension</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Array</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">where</span><span style="font-variant-ligatures: no-common-ligatures" class=""> Element: FloatingPoint {</span></div><p 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="webkit-block-placeholder"></p><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">func</span><span style="font-variant-ligatures: no-common-ligatures" class=""> sum() -> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Element</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">guard</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">count</span><span style="font-variant-ligatures: no-common-ligatures" class=""> > </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">else</span><span style="font-variant-ligatures: no-common-ligatures" class=""> { </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">switch</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">self</span><span style="font-variant-ligatures: no-common-ligatures" class="">[</span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">case</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">is</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Double</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result = </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Double</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">vDSP_sveD</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">unsafeBitCast</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">self</span><span style="font-variant-ligatures: no-common-ligatures" class="">, to: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Array</span><span style="font-variant-ligatures: no-common-ligatures" class=""><</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Double</span><span style="font-variant-ligatures: no-common-ligatures" class="">>.</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">self</span><span style="font-variant-ligatures: no-common-ligatures" class="">), </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">, &result, </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">vDSP_Length</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">count</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">print</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">"vDSP"</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">unsafeBitCast</span><span style="font-variant-ligatures: no-common-ligatures" class="">(result, to: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Element</span><span style="font-variant-ligatures: no-common-ligatures" class="">.</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">self</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">case</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">is</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Float</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result = </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Float</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">vDSP_sve</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">unsafeBitCast</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">self</span><span style="font-variant-ligatures: no-common-ligatures" class="">, to: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Array</span><span style="font-variant-ligatures: no-common-ligatures" class=""><</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Float</span><span style="font-variant-ligatures: no-common-ligatures" class="">>.</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">self</span><span style="font-variant-ligatures: no-common-ligatures" class="">), </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">, &result, </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">vDSP_Length</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">count</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">print</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">"vDSP"</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">unsafeBitCast</span><span style="font-variant-ligatures: no-common-ligatures" class="">(result, to: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Element</span><span style="font-variant-ligatures: no-common-ligatures" class="">.</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">self</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">default</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">print</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">"default"</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">reduce</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</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" 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" 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" class="">}</span></div></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="">But this is not very efficient, especially if it is defined in another module, which limits optimizations.</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="">Instead, a family of overloaded global functions gives you the most coverage and best performance, at the expense of repetition and boilerplate code:</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=""><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="">func</span><span style="font-variant-ligatures: no-common-ligatures" class=""> sum<S: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Sequence</span><span style="font-variant-ligatures: no-common-ligatures" class="">>(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">_</span><span style="font-variant-ligatures: no-common-ligatures" class=""> sequence: </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">S</span><span style="font-variant-ligatures: no-common-ligatures" class="">) -> </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">S</span><span style="font-variant-ligatures: no-common-ligatures" class="">.Iterator.Element </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">where</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">S</span><span style="font-variant-ligatures: no-common-ligatures" class="">.Iterator.Element: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Integer</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result: </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">S</span><span style="font-variant-ligatures: no-common-ligatures" class="">.Iterator.Element = </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">for</span><span style="font-variant-ligatures: no-common-ligatures" class=""> element </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">in</span><span style="font-variant-ligatures: no-common-ligatures" class=""> sequence { result += element }</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</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="">func</span><span style="font-variant-ligatures: no-common-ligatures" class=""> sum<S: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Sequence</span><span style="font-variant-ligatures: no-common-ligatures" class="">>(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">_</span><span style="font-variant-ligatures: no-common-ligatures" class=""> sequence: </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">S</span><span style="font-variant-ligatures: no-common-ligatures" class="">) -> </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">S</span><span style="font-variant-ligatures: no-common-ligatures" class="">.Iterator.Element </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">where</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">S</span><span style="font-variant-ligatures: no-common-ligatures" class="">.Iterator.Element: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">FloatingPoint</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result: </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">S</span><span style="font-variant-ligatures: no-common-ligatures" class="">.Iterator.Element = </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">for</span><span style="font-variant-ligatures: no-common-ligatures" class=""> element </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">in</span><span style="font-variant-ligatures: no-common-ligatures" class=""> sequence { result += element }</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</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="">func</span><span style="font-variant-ligatures: no-common-ligatures" class=""> sum(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">_</span><span style="font-variant-ligatures: no-common-ligatures" class=""> array: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Array</span><span style="font-variant-ligatures: no-common-ligatures" class=""><</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Double</span><span style="font-variant-ligatures: no-common-ligatures" class="">>) -> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Double</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result = </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Double</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">vDSP_sveD</span><span style="font-variant-ligatures: no-common-ligatures" class="">(array, </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">, &result, </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">vDSP_Length</span><span style="font-variant-ligatures: no-common-ligatures" class="">(array.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">count</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</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; color: rgb(112, 61, 170);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">func</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> sum(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">_</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> array: </span><span style="font-variant-ligatures: no-common-ligatures" class="">ContiguousArray</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""><</span><span style="font-variant-ligatures: no-common-ligatures" class="">Double</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">>) -> </span><span style="font-variant-ligatures: no-common-ligatures" class="">Double</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" 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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result = </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Double</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" class=""> array.</span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">withUnsafeBufferPointer</span><span style="font-variant-ligatures: no-common-ligatures" class=""> { </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">vDSP_sveD</span><span style="font-variant-ligatures: no-common-ligatures" class="">($0.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">baseAddress</span><span style="font-variant-ligatures: no-common-ligatures" class="">!, </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">, &result, </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">vDSP_Length</span><span style="font-variant-ligatures: no-common-ligatures" class="">(array.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">count</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</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="">func</span><span style="font-variant-ligatures: no-common-ligatures" class=""> sum(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">_</span><span style="font-variant-ligatures: no-common-ligatures" class=""> array: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">ArraySlice</span><span style="font-variant-ligatures: no-common-ligatures" class=""><</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Double</span><span style="font-variant-ligatures: no-common-ligatures" class="">>) -> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Double</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result = </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Double</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" class=""> array.</span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">withUnsafeBufferPointer</span><span style="font-variant-ligatures: no-common-ligatures" class=""> { </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">vDSP_sveD</span><span style="font-variant-ligatures: no-common-ligatures" class="">($0.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">baseAddress</span><span style="font-variant-ligatures: no-common-ligatures" class="">!, </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">, &result, </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">vDSP_Length</span><span style="font-variant-ligatures: no-common-ligatures" class="">(array.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">count</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</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="">func</span><span style="font-variant-ligatures: no-common-ligatures" class=""> sum(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">_</span><span style="font-variant-ligatures: no-common-ligatures" class=""> array: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Array</span><span style="font-variant-ligatures: no-common-ligatures" class=""><</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Float</span><span style="font-variant-ligatures: no-common-ligatures" class="">>) -> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Float</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result = </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Float</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">vDSP_sve</span><span style="font-variant-ligatures: no-common-ligatures" class="">(array, </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">, &result, </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">vDSP_Length</span><span style="font-variant-ligatures: no-common-ligatures" class="">(array.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">count</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</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; color: rgb(112, 61, 170);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">func</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> sum(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">_</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> array: </span><span style="font-variant-ligatures: no-common-ligatures" class="">ContiguousArray</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""><</span><span style="font-variant-ligatures: no-common-ligatures" class="">Float</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">>) -> </span><span style="font-variant-ligatures: no-common-ligatures" class="">Float</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" 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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result = </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Float</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" class=""> array.</span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">withUnsafeBufferPointer</span><span style="font-variant-ligatures: no-common-ligatures" class=""> { </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">vDSP_sve</span><span style="font-variant-ligatures: no-common-ligatures" class="">($0.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">baseAddress</span><span style="font-variant-ligatures: no-common-ligatures" class="">!, </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">, &result, </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">vDSP_Length</span><span style="font-variant-ligatures: no-common-ligatures" class="">(array.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">count</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</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="">func</span><span style="font-variant-ligatures: no-common-ligatures" class=""> sum(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">_</span><span style="font-variant-ligatures: no-common-ligatures" class=""> array: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">ArraySlice</span><span style="font-variant-ligatures: no-common-ligatures" class=""><</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Float</span><span style="font-variant-ligatures: no-common-ligatures" class="">>) -> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Float</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result = </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Float</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" class=""> array.</span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">withUnsafeBufferPointer</span><span style="font-variant-ligatures: no-common-ligatures" class=""> { </span><span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">vDSP_sve</span><span style="font-variant-ligatures: no-common-ligatures" class="">($0.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">baseAddress</span><span style="font-variant-ligatures: no-common-ligatures" class="">!, </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">1</span><span style="font-variant-ligatures: no-common-ligatures" class="">, &result, </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">vDSP_Length</span><span style="font-variant-ligatures: no-common-ligatures" class="">(array.</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">count</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" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> result</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div><div class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div></span></div><div class="">The above code covers summing any integer or floating point sequence of numbers, while being accelerated for Float and Double array types (Array, ContiguousArray and ArraySlice)</div><div class=""><br class=""></div><div class=""><div class=""><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Nov 21, 2016, at 4:32 PM, Rick Mann via swift-users <<a href="mailto:swift-users@swift.org" class="">swift-users@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">My googling is not turning up an answer that works in Xcode 8.1. I'd like to do this:<br class=""><br class=""><br class="">import Accelerate<br class=""><br class="">extension<br class="">Array<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>where Element == Double<br class="">{<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>func<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>sum()<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>-> Double<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>{<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>var result: Double = 0.0<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>vDSP_sveD(self, 1, &result, vDSP_Length(self.count))<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>return result<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>}<br class="">}<br class=""><br class="">But I get "same-type requirement makes generic parameter 'Element' non-generic."<br class=""><br class="">Also, will there ever be any way to specialize something like<br class=""><br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>let numbers: [Double] = ...<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>let sum = numbers.reduce(0.0, +)<br class=""><br class="">Into a call to vDSP_sveD()? Would it require compiler optimizations for Accelerate?<br class=""><br class="">Thanks!<br class=""><br class="">-- <br class="">Rick Mann<br class=""><a href="mailto:rmann@latencyzero.com" class="">rmann@latencyzero.com</a><br class=""><br class=""><br class="">_______________________________________________<br class="">swift-users mailing list<br class="">swift-users@swift.org<br class="">https://lists.swift.org/mailman/listinfo/swift-users<br class=""></div></div></blockquote></div><br class=""></div></div></div></body></html>