ely on
      compiler optimizations being turned on to give really good performance. Also,
      since the return type from expressions involving <code class="computeroutput"><span class="identifier">number</span></code>s
      is an "unmentionable implementation detail", you have to be careful
      to cast the result of an expression to the actual number type when passing
      an expression to a template function. For example, given:
    </p>
<pre class="programlisting"><span class="keyword">template</sp