 <p>You can't do that unless the subroutine is a built-in Perl operator, like <code>sqrt</code> for instance, when you could write</p> <pre><code>perl -e "print sqrt(2)" </code></pre> <p>or if it is provided by an installed module, say <a href="https://metacpan.org/module/List%3a%3aUtil" rel="nofollow"><code>List::Util</code></a>, like this</p> <pre><code>perl -MList::Util=shuffle -e "print shuffle 'A' .. 'Z'" </code></pre>