37 lines
No EOL
2.2 KiB
HTML
37 lines
No EOL
2.2 KiB
HTML
<!doctype html>
|
||
<html lang="en">
|
||
<head>
|
||
<meta charset="utf-8">
|
||
<meta name="viewport" content="width=device-width, initial-scale=1">
|
||
<title>is_err — Ludic</title>
|
||
<meta name="description" content="True when a result carries a failure.">
|
||
<link rel="stylesheet" href="base.css">
|
||
<link rel="stylesheet" href="docs.css">
|
||
</head>
|
||
<body>
|
||
<header class="nav"><div class="wrap nav-in"><a class="brand" href="index.html"><span class="logo">L</span> Ludic</a><button class="nav-toggle" aria-label="Toggle menu" aria-expanded="false">☰</button><nav class="nav-links"><a href="index.html">Home</a><a href="api.html">API Reference</a><a class="nav-cta" href="https://git.workshopsoft.io/workshopsoft/ludic">Source ↗</a></nav></div></header>
|
||
<main class="wrap item">
|
||
<div class="crumbs"><a href="api.html">API Reference</a> <span>›</span> <a href="api.html#builtins">Builtin functions</a> <span>›</span> <span class="here">is_err</span></div>
|
||
<div class="item-head">
|
||
<span class="kind-badge kind-builtin">function</span>
|
||
<h1 id="top">is_err</h1>
|
||
</div>
|
||
<code class="sig">is_err(r: result) -> bool</code>
|
||
<div class="desc"><p>Tests a <code>result</code>'s tag: <code>true</code> when it was built with <a href="fn-err"><code>err</code></a>, <code>false</code> when it was built with <a href="fn-ok"><code>ok</code></a>. Use it to detect the failure case explicitly — for example to count or log failures — while <a href="kw-try"><code>try</code></a>/<code>else</code> handles recovering a value. It is the exact negation of <a href="fn-is_ok"><code>is_ok</code></a>.</p></div>
|
||
<div class="params"><h2>Parameters</h2><div class="param" id="param-r"><code class="pname">r</code><span class="pdesc">the result to test</span></div></div>
|
||
<div class="examples"><h2>Example</h2><pre data-lang="ludic">program Retry {
|
||
function step(n: int) -> result {
|
||
if n < 3 { return err("not ready") }
|
||
return ok(n)
|
||
}
|
||
test "is_err detects the failure case" {
|
||
expect(is_err(step(1)))
|
||
expect(not is_err(step(5)))
|
||
}
|
||
}</pre></div>
|
||
|
||
<a class="back" href="api.html">← All symbols</a>
|
||
</main>
|
||
<script src="ludic-highlight.js"></script>
|
||
<script>Ludic.highlightAll(); Ludic.installCards(); Ludic.flashTarget();</script>
|
||
</body></html> |