Nice summary. I like it. I will bookmark it for future reference as it is more concise than the Wikipedia article that I usually refer to.<p>A quick mention about closures would be a good idea.<p>I often see the Lambda Calculus introduced with &quot;oh look only 3 constructs and you can do all this stuff...&quot;<p>However closures are also necessary because if the inner `x` in<p><pre><code>  \x.(\x.x)
</code></pre>
doesn&#x27;t come from the correct abstraction the whole thing doesn&#x27;t work.