es:</p>
<pre><code class="lang-javascript">var title = stream(&quot;&quot;)
var slug = title.map(function(value) {
    return value.toLowerCase().replace(/\W/g, &quot;-&quot;)
})

title(&quot;Hello world&quot;)
console.log(slug()) // logs &quot;hello-world&quot;
</code></pre>
<p>In the example above, the value of <code>slug</code> is computed when <code>title</code> is updated, not when <code>slug</code> is read.</p>
<p>It&#39;s of course also possible to compute properties based on multiple streams:</p>
<p