 where
<code>_f</code> is a notional temporary variable (not visible or
produces as a side-effect). This effect is used in <code>wrapr</code>’s
“pipe to array” variation of the <code>unpack</code> notation (example
<a href="https://win-vector.com/2020/01/21/using-unpack-to-manage-your-r-environment/" class="external-link">here</a>).</p>
<p>This eager effect can be gotten by setting the appropriate attribute
as we see below.</p>
<p>For array notation:</p>
<div class="sourceCode" id="cb1"><pre class="do