Evaluate Irrational with Julia : <p>Julia has the built-in constant <code>pi</code>, with type <code>Irrational</code>.</p>

<pre><code>julia&gt; pi
π = 3.1415926535897...

julia&gt; π
π = 3.1415926535897...

julia&gt; typeof(pi)
Irrational{:π}
</code></pre>

<p>Coming from SymPy, which has the <code>N()</code> function, I would like to evaluate <code>pi</code> (or other <code>Irrational</code>s, such as <code>e</code>, <code>golden</code>, etc.) to n digits.</p>

<pre><code>In [5]: N(pi, n=50)
Out[5]: 3.1415926535897932384626433832795028841971693993751
</code></pre>

<p>Is this possible? I am assuming that <code>pi</code> is based on its mathematical definition, rather than just to thirteen decimal places.</p>
