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diff --git a/public/posts/2024-08-31-01 b/public/posts/2024-08-31-01 new file mode 100644 index 0000000..1c25a70 --- /dev/null +++ b/public/posts/2024-08-31-01 @@ -0,0 +1,107 @@ + +<!DOCTYPE html> +<html lang="en"> + +<head> + <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> + <meta name="description" content="Home for a73x" /> + <meta name="author" content="a73x" /> + <meta name="viewport" + content="user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, width=device-width" /> + <title>a73x</title> + <link rel="stylesheet" href="/static/styles.css"> + <link rel="stylesheet" href="/static/syntax.css"> + <link rel="icon" type="image/x-icon" href="/static/favicon.svg"> +</head> + +<body> + <main> + <div class="header"> + <div class="header-title"> + <h1>a73x</h1> + <sub>high effort, low reward</sub> + </div> + <p>[{home /} {posts /posts} {ethos /ethos}]</p> + <p>posts/2024-08-31-01.html</p> + <nav class="nav"> + <ul> + + + <li><a class="no-decorations" href="/">home</a></li> + + + + <li><a class="no-decorations" href="/posts">posts</a></li> + + + + <li><a class="no-decorations" href="/ethos">ethos</a></li> + + + </ul> + </nav> + </div> + +<a href="/posts">← Posts</a> +<h1>Go's unique pkg</h1> +<p><a href="https://pkg.go.dev/unique">https://pkg.go.dev/unique</a></p> + +<blockquote> +<p>The unique package provides facilities for canonicalising (“interning”) comparable values.<sup class="footnote-ref" id="fnref:1"><a href="#fn:1">1</a></sup></p> +</blockquote> + +<p>oh yeah, thats obvious I fully understand what this package does now, great read, tune in for the next post.</p> + +<p>Interning, is the re-use of an object of equal value instead of creating a new one. I’m pretending I knew this but really I’ve just reworded <a href="https://en.wikipedia.org/wiki/Interning_(computer_science)">Interning</a>.</p> + +<p>So lets try again.</p> + +<p>If you’re parsing out a csv of bank transactions, its very likely a lot of names will be repeated. Instead of allocating memory for each string representing a merchant, you can simply reuse the the same string.</p> + +<p>So the dumbed down version might look like</p> +<pre tabindex="0" class="chroma"><code><span class="line"><span class="cl"><span class="kd">var</span> <span class="nx">internedStrings</span> <span class="nx">sync</span><span class="p">.</span><span class="nx">Map</span> +</span></span><span class="line"><span class="cl"> +</span></span><span class="line"><span class="cl"><span class="kd">func</span> <span class="nf">Intern</span><span class="p">(</span><span class="nx">s</span> <span class="kt">string</span><span class="p">)</span> <span class="kt">string</span> <span class="p">{</span> +</span></span><span class="line"><span class="cl"> <span class="k">if</span> <span class="nx">val</span><span class="p">,</span> <span class="nx">ok</span> <span class="o">:=</span> <span class="nx">internedStrings</span><span class="p">.</span><span class="nf">Load</span><span class="p">(</span><span class="nx">s</span><span class="p">);</span> <span class="nx">ok</span> <span class="p">{</span> +</span></span><span class="line"><span class="cl"> <span class="k">return</span> <span class="nx">val</span><span class="p">.(</span><span class="kt">string</span><span class="p">)</span> +</span></span><span class="line"><span class="cl"> <span class="p">}</span> +</span></span><span class="line"><span class="cl"> <span class="nx">internedStrings</span><span class="p">.</span><span class="nf">Store</span><span class="p">(</span><span class="nx">s</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span> +</span></span><span class="line"><span class="cl"> <span class="k">return</span> <span class="nx">s</span> +</span></span><span class="line"><span class="cl"><span class="p">}</span> +</span></span></code></pre> +<p>With a small demo here <a href="https://go.dev/play/p/piSYjCHIcLr">https://go.dev/play/p/piSYjCHIcLr</a></p> + +<p>This implementation is fairly naive, it can only grow and it only works with strings, so naturally go’s implementation is a better.</p> + +<p>It’s also worth noting, that since strings are a pointer under the hood</p> + +<blockquote> +<p>When comparing two strings, if the pointers are not equal, then we must compare their contents to determine equality. But if we know that two strings are canonicalized, then it <em>is</em> sufficient to just check their pointers.<sup class="footnote-ref" id="fnref:2"><a href="#fn:2">2</a></sup></p> +</blockquote> + +<p>So to recap, goes <code>unique</code> package provides a way to reuse objects instead of creating new ones, if we consider the objects of equal value.</p> + +<div class="footnotes"> + +<hr> + +<ol> +<li id="fn:1"><a href="https://pkg.go.dev/unique">https://pkg.go.dev/unique</a> <a class="footnote-return" href="#fnref:1"><sup>[return]</sup></a></li> + +<li id="fn:2"><a href="https://go.dev/blog/unique">https://go.dev/blog/unique</a> <a class="footnote-return" href="#fnref:2"><sup>[return]</sup></a></li> +</ol> + +</div> + + + <footer> + <br /> + <hr /> + <br /> + <p>see something you disagree with? email: <a href="mailto:[email protected]">[email protected]</a></p> + </footer> + </main> +</body> + +</html> + |