title: Boolean values in Scheme
body: <pre><code>(define true (lambda (x y) x))
  
  (define false (lambda (x y) y))
  </code></pre>
  
  <p>So <code>(true 1 2)</code> will give 1, while <code>(false 1 2)</code> gives 2.</p>
  
  <p>Based on this, how should I write a <code>(not true)</code> procedure which will give false and <code>(not false)</code> will give me a true using lambda expressions. (As simply as I can.)</p>
  
  <p><code>(define not p)</code> ...etc</p>