</a>Beta-reduction</h3>
<p>An important question is: what is the semantics of the lambda-calculus? The theoretical beauty of the calculus is that it mostly relies on a single (at least apparently) simple rewrite rule: <em>beta-reduction</em>.</p>
<p>Let’s consider again the identity function, called on an argument:</p>
<pre><code class="language-clojure">((fn [x] x) 42)
</code></pre>
<p>While for practical reasons (especially efficiency) things are much more complex, the computation triggered here can be 