<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Hi,<div class=""><br class=""></div><div class="">A short proposal for you as part of the algorithms theme. Hopefully non-controversial, aside from the naming of the method and arguments, about which controversy abounds. Online copy here: <a href="https://github.com/airspeedswift/swift-evolution/blob/9a778e904c9be8a3692edd19bb757b23c54aacbe/proposals/0162-all-algorithm.md" class="">https://github.com/airspeedswift/swift-evolution/blob/9a778e904c9be8a3692edd19bb757b23c54aacbe/proposals/0162-all-algorithm.md</a></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><h1 id="add-an--code-all--code--algorithm-to--code-sequence--code-" style="box-sizing: border-box; font-size: 2.25em; margin-right: 0px; margin-bottom: 16px; margin-left: 0px; line-height: 1.2; position: relative; color: rgb(51, 51, 51); padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); font-family: helvetica, arial, freesans, clean, sans-serif; background-color: rgb(255, 255, 255); margin-top: 0px !important;" class="">Add an <code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 24.479999542236328px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">all</code> algorithm to <code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 24.479999542236328px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">Sequence</code></h1><ul style="box-sizing: border-box; padding: 0px 0px 0px 2em; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: helvetica, arial, freesans, clean, sans-serif; font-size: 12.799999237060547px; background-color: rgb(255, 255, 255);" class=""><li style="box-sizing: border-box;" class="">Proposal: <a href="file:///Users/ben_cohen/Documents/swift-evolution/proposals/0162-all-algorithm.md" style="box-sizing: border-box; background-color: transparent; color: rgb(65, 131, 196); text-decoration: none;" class="">SE-NNNN</a></li><li style="box-sizing: border-box;" class="">Authors: <a href="https://github.com/airspeedswift" style="box-sizing: border-box; background-color: transparent; color: rgb(65, 131, 196); text-decoration: none;" class="">Ben Cohen</a></li><li style="box-sizing: border-box;" class="">Review Manager: TBD</li><li style="box-sizing: border-box;" class="">Status: <strong style="box-sizing: border-box;" class="">Awaiting review</strong></li></ul><h2 id="introduction" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; position: relative; color: rgb(51, 51, 51); padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); font-family: helvetica, arial, freesans, clean, sans-serif; background-color: rgb(255, 255, 255);" class="">Introduction</h2><p style="box-sizing: border-box; margin: 0px 0px 16px; color: rgb(51, 51, 51); font-family: helvetica, arial, freesans, clean, sans-serif; font-size: 12.799999237060547px; background-color: rgb(255, 255, 255);" class="">It is common to want to confirm that every element of a sequence equals a value, or matches a certain criteria. Many implementations of this can be found in use on github. This proposal adds such a method to <code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 10.880000114440918px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">Sequence</code>.</p><h2 id="motivation" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; position: relative; color: rgb(51, 51, 51); padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); font-family: helvetica, arial, freesans, clean, sans-serif; background-color: rgb(255, 255, 255);" class="">Motivation</h2><p style="box-sizing: border-box; margin: 0px 0px 16px; color: rgb(51, 51, 51); font-family: helvetica, arial, freesans, clean, sans-serif; font-size: 12.799999237060547px; background-color: rgb(255, 255, 255);" class="">You can achieve this in Swift 3 with <code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 10.880000114440918px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">contains</code> by negating both the criteria and the result:</p><pre style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 10.880000114440918px; margin-top: 0px; margin-bottom: 16px; font-stretch: normal; line-height: 1.45; padding: 16px; background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; tab-size: 4; color: rgb(51, 51, 51); height: 103px;" class=""><code class="swift hljs" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; padding: 0.5em; margin: 0px; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; border: 0px; display: block; overflow-x: auto; line-height: inherit; word-wrap: normal; height: auto;"><span class="hljs-comment" style="box-sizing: border-box; color: rgb(153, 153, 136); font-style: italic;">// every element is 9</span>
!nums.<span class="hljs-built_in" style="box-sizing: border-box; color: rgb(0, 134, 179);">contains</span> { $<span class="hljs-number" style="box-sizing: border-box; color: rgb(0, 128, 128);">0</span> != <span class="hljs-number" style="box-sizing: border-box; color: rgb(0, 128, 128);">9</span> }
<span class="hljs-comment" style="box-sizing: border-box; color: rgb(153, 153, 136); font-style: italic;">// every element is odd</span>
!nums.<span class="hljs-built_in" style="box-sizing: border-box; color: rgb(0, 134, 179);">contains</span> { !isOdd($<span class="hljs-number" style="box-sizing: border-box; color: rgb(0, 128, 128);">0</span>) }</code></pre><p style="box-sizing: border-box; margin: 0px 0px 16px; color: rgb(51, 51, 51); font-family: helvetica, arial, freesans, clean, sans-serif; font-size: 12.799999237060547px; background-color: rgb(255, 255, 255);" class="">but these are a readability nightmare. Additionally, developers may not make the leap to realize <code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 10.880000114440918px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">contains</code> can be used this way, so may hand-roll their own <code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 10.880000114440918px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">for</code> loop, which could be buggy<ins id="firstdiff" style="box-sizing: border-box; display: inline-block; position: absolute; left: -8px; text-decoration: none !important; border: none !important; background-image: none !important; background-position: initial initial !important; background-repeat: initial initial !important;" class=""></ins>, or compose other inefficient alternatives:</p><pre style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 10.880000114440918px; margin-top: 0px; margin-bottom: 16px; font-stretch: normal; line-height: 1.45; padding: 16px; background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; tab-size: 4; color: rgb(51, 51, 51); height: 103px;" class=""><code class="swift hljs" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; padding: 0.5em; margin: 0px; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; border: 0px; display: block; overflow-x: auto; line-height: inherit; word-wrap: normal; height: auto;"><span class="hljs-comment" style="box-sizing: border-box; color: rgb(153, 153, 136); font-style: italic;">// misses opportunity to bail early</span>
nums.<span class="hljs-built_in" style="box-sizing: border-box; color: rgb(0, 134, 179);">reduce</span>(<span class="hljs-literal" style="box-sizing: border-box; color: rgb(0, 128, 128);">true</span>) { $<span class="hljs-number" style="box-sizing: border-box; color: rgb(0, 128, 128);">0.0</span> && $<span class="hljs-number" style="box-sizing: border-box; color: rgb(0, 128, 128);">0.1</span> == <span class="hljs-number" style="box-sizing: border-box; color: rgb(0, 128, 128);">9</span> }
<span class="hljs-comment" style="box-sizing: border-box; color: rgb(153, 153, 136); font-style: italic;">// the most straw-man travesty I could think of...</span>
<span class="hljs-type" style="box-sizing: border-box; color: rgb(68, 85, 136); font-weight: bold;">Set</span>(nums).<span class="hljs-built_in" style="box-sizing: border-box; color: rgb(0, 134, 179);">count</span> == <span class="hljs-number" style="box-sizing: border-box; color: rgb(0, 128, 128);">1</span> && <span class="hljs-type" style="box-sizing: border-box; color: rgb(68, 85, 136); font-weight: bold;">Set</span>(nums).first == <span class="hljs-number" style="box-sizing: border-box; color: rgb(0, 128, 128);">9</span></code></pre><h2 id="proposed-solution" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; position: relative; color: rgb(51, 51, 51); padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); font-family: helvetica, arial, freesans, clean, sans-serif; background-color: rgb(255, 255, 255);" class="">Proposed solution</h2><p style="box-sizing: border-box; margin: 0px 0px 16px; color: rgb(51, 51, 51); font-family: helvetica, arial, freesans, clean, sans-serif; font-size: 12.799999237060547px; background-color: rgb(255, 255, 255);" class="">Introduce two algorithms on <code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 10.880000114440918px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">Sequence</code> which test every element and return <code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 10.880000114440918px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">true</code> if they match:</p><pre style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 10.880000114440918px; margin-top: 0px; margin-bottom: 16px; font-stretch: normal; line-height: 1.45; padding: 16px; background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; tab-size: 4; color: rgb(51, 51, 51); height: 73px;" class=""><code class="swift hljs" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; padding: 0.5em; margin: 0px; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; border: 0px; display: block; overflow-x: auto; line-height: inherit; word-wrap: normal; height: auto;">nums.all(<span class="hljs-built_in" style="box-sizing: border-box; color: rgb(0, 134, 179);">equal</span>: <span class="hljs-number" style="box-sizing: border-box; color: rgb(0, 128, 128);">9</span>)
nums.all(match: isOdd)</code></pre><h2 id="detailed-design" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; position: relative; color: rgb(51, 51, 51); padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); font-family: helvetica, arial, freesans, clean, sans-serif; background-color: rgb(255, 255, 255);" class="">Detailed design</h2><p style="box-sizing: border-box; margin: 0px 0px 16px; color: rgb(51, 51, 51); font-family: helvetica, arial, freesans, clean, sans-serif; font-size: 12.799999237060547px; background-color: rgb(255, 255, 255);" class="">Add the following extensions to <code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 10.880000114440918px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;" class="">Sequence</code>:</p><pre style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 10.880000114440918px; margin-top: 0px; margin-bottom: 16px; font-stretch: normal; line-height: 1.45; padding: 16px; background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; tab-size: 4; color: rgb(51, 51, 51); height: 208px;" class=""><code class="swift hljs" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; padding: 0.5em; margin: 0px; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; border: 0px; display: block; overflow-x: auto; line-height: inherit; word-wrap: normal; height: auto;"><span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="box-sizing: border-box; font-weight: bold;">extension</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(68, 85, 136); font-weight: bold;">Sequence</span> </span>{
<span class="hljs-comment" style="box-sizing: border-box; color: rgb(153, 153, 136); font-style: italic;">/// Returns a Boolean value indicating whether every element of the sequence</span>
<span class="hljs-comment" style="box-sizing: border-box; color: rgb(153, 153, 136); font-style: italic;">/// satisfies the given predicate.</span>
<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="box-sizing: border-box; font-weight: bold;">func</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(153, 0, 0); font-weight: bold;">all</span><span class="hljs-params" style="box-sizing: border-box;">(match criteria: <span class="hljs-params" style="box-sizing: border-box;">(Iterator.Element)</span></span></span> <span class="hljs-keyword" style="box-sizing: border-box; font-weight: bold;">throws</span> -> <span class="hljs-type" style="box-sizing: border-box; color: rgb(68, 85, 136); font-weight: bold;">Bool</span>) <span class="hljs-keyword" style="box-sizing: border-box; font-weight: bold;">rethrows</span> -> <span class="hljs-type" style="box-sizing: border-box; color: rgb(68, 85, 136); font-weight: bold;">Bool</span>
}
<span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="box-sizing: border-box; font-weight: bold;">extension</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(68, 85, 136); font-weight: bold;">Sequence</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(68, 85, 136); font-weight: bold;">where</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(68, 85, 136); font-weight: bold;">Iterator</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(68, 85, 136); font-weight: bold;">Element</span>: <span class="hljs-title" style="box-sizing: border-box; color: rgb(68, 85, 136); font-weight: bold;">Equatable</span> </span>{
<span class="hljs-comment" style="box-sizing: border-box; color: rgb(153, 153, 136); font-style: italic;">/// Returns a Boolean value indicating whether every element of the sequence</span>
<span class="hljs-comment" style="box-sizing: border-box; color: rgb(153, 153, 136); font-style: italic;">/// equals the given element.</span>
<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="box-sizing: border-box; font-weight: bold;">func</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(153, 0, 0); font-weight: bold;">all</span><span class="hljs-params" style="box-sizing: border-box;">(<span class="hljs-built_in" style="box-sizing: border-box; color: rgb(0, 134, 179);">equal</span> element: Iterator.Element)</span></span> -> <span class="hljs-type" style="box-sizing: border-box; color: rgb(68, 85, 136); font-weight: bold;">Bool</span>
}</code></pre><h2 id="source-compatibility" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; position: relative; color: rgb(51, 51, 51); padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); font-family: helvetica, arial, freesans, clean, sans-serif; background-color: rgb(255, 255, 255);" class="">Source compatibility</h2><p style="box-sizing: border-box; margin: 0px 0px 16px; color: rgb(51, 51, 51); font-family: helvetica, arial, freesans, clean, sans-serif; font-size: 12.799999237060547px; background-color: rgb(255, 255, 255);" class="">This change is purely additive so has no source compatibility consequences.</p><h2 id="effect-on-abi-stability" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; position: relative; color: rgb(51, 51, 51); padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); font-family: helvetica, arial, freesans, clean, sans-serif; background-color: rgb(255, 255, 255);" class="">Effect on ABI stability</h2><p style="box-sizing: border-box; margin: 0px 0px 16px; color: rgb(51, 51, 51); font-family: helvetica, arial, freesans, clean, sans-serif; font-size: 12.799999237060547px; background-color: rgb(255, 255, 255);" class="">This change is purely additive so has no ABI stability consequences.</p><h2 id="effect-on-api-resilience" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; position: relative; color: rgb(51, 51, 51); padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); font-family: helvetica, arial, freesans, clean, sans-serif; background-color: rgb(255, 255, 255);" class="">Effect on API resilience</h2><p style="box-sizing: border-box; margin: 0px 0px 16px; color: rgb(51, 51, 51); font-family: helvetica, arial, freesans, clean, sans-serif; font-size: 12.799999237060547px; background-color: rgb(255, 255, 255);" class="">This change is purely additive so has no API resilience consequences.</p><h2 id="alternatives-considered" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; position: relative; color: rgb(51, 51, 51); padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); font-family: helvetica, arial, freesans, clean, sans-serif; background-color: rgb(255, 255, 255);" class="">Alternatives considered</h2><div style="box-sizing: border-box; margin-top: 0px; margin-right: 0px; margin-left: 0px; color: rgb(51, 51, 51); font-family: helvetica, arial, freesans, clean, sans-serif; font-size: 12.799999237060547px; background-color: rgb(255, 255, 255); margin-bottom: 0px !important;" class="">Not adding it.</div></div></body></html>