Cannot use a required namespaced class
<p>I have:</p>

<pre><code>(ns test-1.core
  (:require [goog.dom :as dom]
            [goog.ui.Popup :as popup]
            [goog.positioning.AbsolutePosition]
            [rum.core :as rum]))
</code></pre>

<p>Now I can:</p>

<pre><code>(dom/getElement "popup")
</code></pre>

<p>but for reasons I don't understand I cannot do :</p>

<pre><code>(popup. .....)
</code></pre>

<p>Instead, I have to write:</p>

<pre><code>(goog.ui.Popup. .....)
</code></pre>

<p>Why?</p>