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<nav id="sidebar" class="sidebar" aria-label="Table of contents"> <div class="sidebar-scrollbox"> <ol class="chapter"><li class="spacer"></li><li class="chapter-item expanded affix "><a href="introduction.html" class="active">Introduction</a></li><li class="chapter-item expanded affix "><li class="part-title">Processes</li><li class="chapter-item expanded "><a href="process-run.html"><strong aria-hidden="true">1.</strong> Running a Process</a></li><li class="chapter-item expanded "><a href="process-output.html"><strong aria-hidden="true">2.</strong> Output</a></li><li class="chapter-item expanded "><a href="process-input.html"><strong aria-hidden="true">3.</strong> Input</a></li><li class="chapter-item expanded "><a href="process-stderr.html"><strong aria-hidden="true">4.</strong> Stderr and Error Handling</a></li><li class="chapter-item expanded affix "><li class="part-title">Input/Output</li><li class="chapter-item expanded "><a href="io/read.html"><strong aria-hidden="true">5.</strong> Reading Stuff</a></li><li class="chapter-item expanded "><div><strong aria-hidden="true">6.</strong> Writing Stuff</div></li><li class="chapter-item expanded affix "><li class="part-title">Higher Order Functions for AsyncIterable</li><li class="chapter-item expanded "><div><strong aria-hidden="true">7.</strong> Enumeration</div></li><li class="chapter-item expanded "><div><strong aria-hidden="true">8.</strong> Compatibility with Streams</div></li><li class="chapter-item expanded "><a href="performance.html"><strong aria-hidden="true">9.</strong> Performance</a></li><li class="chapter-item expanded affix "><li class="part-title">Concurrency and Parallel Processing</li><li class="chapter-item expanded affix "><li class="part-title">Miscellaneous</li><li class="chapter-item expanded "><a href="misc/sleep.html"><strong aria-hidden="true">10.</strong> Sleep</a></li><li class="chapter-item expanded "><div><strong aria-hidden="true">11.</strong> Range</div></li><li class="chapter-item expanded "><div><strong aria-hidden="true">12.</strong> Shuffle</div></li><li class="chapter-item expanded affix "><li class="part-title">Concepts</li><li class="chapter-item expanded "><a href="text-data.html"><strong aria-hidden="true">13.</strong> Working with Text Data</a></li><li class="chapter-item expanded "><a href="transform.html"><strong aria-hidden="true">14.</strong> Transformers</a></li><li class="chapter-item expanded affix "><li class="part-title">Examples</li><li class="chapter-item expanded "><div><strong aria-hidden="true">15.</strong> Embed a Bash Script</div></li><li class="chapter-item expanded "><a href="example-counting-words.html"><strong aria-hidden="true">16.</strong> Counting Words</a></li><li class="chapter-item expanded "><a href="example-concurrent-processing.html"><strong aria-hidden="true">17.</strong> Concurrent Processing</a></li><li class="chapter-item expanded "><a href="example-io.html"><strong aria-hidden="true">18.</strong> Input and Output</a></li></ol> </div> <div id="sidebar-resize-handle" class="sidebar-resize-handle"> <div class="sidebar-resize-indicator"></div> </div> </nav>
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<h1 class="menu-title">proc</h1>
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<div id="content" class="content"> <main> <h1 id="proc-0218"><a class="header" href="#proc-0218"><code>proc 0.21.8</code></a></h1><p><code>proc</code> let's you use child processes with<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/AsyncIterator"><code>AsyncIterable</code></a>instead of the streams API, and it includes a library of higher-order functionsfor <code>AsyncIterator</code> via<a href="https://deno.land/x/proc@0.21.8/mod.ts?s=Enumerable"><code>Enumerable</code></a> thatroughly matches what you can do with an array (<code>map</code>, <code>filter</code>, <code>find</code>), but forasynchronous code.</p><p><code>proc</code> simplifies the process of converting a <code>bash</code> script into a Denoapplication. The intention is to make writing code that uses lots of IO andchild processes <em>almost</em> as easy as shell scripting, but you also get propererror handling, type checking, and Deno's security-by-default.</p><p><a href="https://deno.land/x/proc@0.21.8/mod.ts">Developer Documentation</a></p><h2 id="usage"><a class="header" href="#usage">Usage</a></h2><pre><code class="language-typescript">import { run } from "https://deno.land/x/proc@0.21.8/mod.ts";</code></pre><h2 id="a-simple-example"><a class="header" href="#a-simple-example">A Simple Example</a></h2><p>Run <code>ls -la</code> as a child process. Decode <code>stdout</code> as lines of text. Print toconsole.</p><pre><code class="language-typescript">await run("ls", "-la").toStdout();</code></pre><h2 id="a-better-example"><a class="header" href="#a-better-example">A Better Example</a></h2><p>Don't worry about understanding everything in this example yet. This shows alittle of what is possible using <code>proc</code>.</p><p>Given the text for <em>War and Peace</em>:</p><ul><li>Read the file into an <code>AsyncIterable</code> of <code>Uint8Array</code>.</li><li>Uncompress it (the file is GZ'd).</li><li>Convert to lowercase using JavaScript, because the JavaScript conversion ismore correct than the one in <code>tr</code>.</li><li><code>grep</code> out all the words on word boundaries.</li><li><code>tee</code> this into two streams (<code>AsyncIterable</code> of <code>Uint8Array</code>) of words.<ul><li>Count the total number of words.</li><li>Use <code>sort</code> with <code>uniq</code> to count the unique words.</li></ul></li></ul><pre><code class="language-typescript">const [words1, words2] = read( fromFileUrl(import.meta.resolve("./warandpeace.txt.gz")),) .transform(gunzip) .lines .map((line) => line.toLocaleLowerCase()) .run({ buffer: true }, "grep", "-oE", "(\\w|')+") .tee();
const [uniqueWords, totalWords] = await Promise.all([ words1.run("sort").run("uniq").lines.count(), words2.lines.count(),]);
console.log(`Total: ${totalWords.toLocaleString()}`);console.log(`Unique: ${uniqueWords.toLocaleString()}`);</code></pre><p>Up to the point where we run <code>Promise.all</code>, this is asynchronous, streaming,lazily evaluated code. It is trivially running three child processes (<code>grep</code>,<code>sort</code>, and <code>uniq</code>), a <code>DecompressionStream</code> transform, and in-process logic tonormalize to lower-case. This is all happening concurrently, mostly in parallel,one buffer, one line, or one word at a time.</p>
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