re><code class="lang-javascript">var firstName = stream(&quot;John&quot;)
var lastName = stream(&quot;Doe&quot;)
var fullName = stream.merge([firstName, lastName]).map(function(values) {
    return values.join(&quot; &quot;)
})

console.log(fullName()) // logs &quot;John Doe&quot;

firstName(&quot;Mary&quot;)

console.log(fullName()) // logs &quot;Mary Doe&quot;
</code></pre>
<p>Computed properties in Mithril are updated atomically: streams that depend on multiple streams will never be called more than once