(and thus possibly side-effecting) function.</p>

<p>At runtime, <code class="code">opaque_identity</code> disappears altogether.</p>

<p>A typical use of this function is to prevent pure computations from being
    optimized away in benchmarking loops.  For example:</p>
<pre class="codepre"><code class="code">      <span class="keyword">for</span> _round = 1 <span class="keyword">to</span> 100_000 <span class="keyword">do</span>
        ignore (<span class="constructor">Sys</span>.opaque_identity (my_pure_