Regarding #2: I have a complete version of McCarthy&#x27;s original evaluator at <a href="https:&#x2F;&#x2F;programmingpraxis.com&#x2F;2011&#x2F;11&#x2F;01&#x2F;rip-john-mccarthy&#x2F;" rel="nofollow">https:&#x2F;&#x2F;programmingpraxis.com&#x2F;2011&#x2F;11&#x2F;01&#x2F;rip-john-mccarthy&#x2F;</a>, and it doesn&#x27;t use a single mutation.