Swift How combine to Numeric Type : <p>I am kind of new to Swift, and wonder how to create a combined types.</p>

<pre><code>typealisa Number = Int &amp; Float &amp; Double
</code></pre>

<p>Isnt work.</p>

<pre><code>public protocol Number {} ;
extension Int : Number {} ;
extension Double : Number {} ;
extension Float : Number {} ;
</code></pre>

<p>When you try </p>

<pre><code>var a : Number = 1 ;
var b : Number = 2 ;
a * b
//Binary operator '*' cannot be applied to two 'Number' operands
</code></pre>

<p>In TS, this cloud be simple as </p>

<pre><code>type Number = Number = Int &amp; Float &amp; Double
</code></pre>

<p>Thank you so much!</p>
