The language being defined here is not a Lisp, it&#x27;s a (trivial) language that just happens to use (something like) S expressions as the surface syntax.  (The reason it&#x27;s only &quot;something like&quot; S expressions is that it has ad-hoc commas to delimit argument lists.)<p>The characteristic that defines a Lisp is that code is not a sequence of characters, it&#x27;s a data structure -- typically a tree of cons cells -- which can be manipulated within the language itself.  The language being defined here doesn&#x27;t have that property.<p>It is this property that allows you to write macros, which is what makes Lisp cool.  Without it you don&#x27;t have Lisp, you just have a run-of-the-mill programming language with weird syntax.