Swift arguments not allowed when function is assigned to a variable?
<p>Swift 3 requires that all argument labels be included in a function call by default. Yet when a function is assigned to a variable (or constant), and the variable passes arguments, no argument labels are necessary—or even allowed.</p>

<p>For example, for a function with two Int parameters (<code>int1</code> and <code>int2</code>) assigned to a variable called <code>varName</code>:</p>

<pre><code>varName (1, 5) // will work, but
varName (int1: 1, int2: 5) //produces an error for extraneous argument labels.
</code></pre>

<ol>
<li><p>Is my understanding correct?</p></li>
<li><p>What is the rationale for not requiring argument labels here? (I can’t find any documentation on this.)</p></li>
</ol>