title: Writing lambda expressions in common lisp
body: <p>I am currently reading ANSI Common Lisp by Paul Graham, and I have a question about writing lambda expressions. </p>
  
  <p>Do we need to prefix a lambda expression with <code>#'</code>?. If I write something like this in REPL, it will work fine</p>
  
  <pre><code>&gt; ((lambda (x) (+ x 1)) 1)
    2
  </code></pre>
  
  <p>so will this</p>
  
  <pre><code>&gt; (mapcar (lambda (x) (+ x x)) '(1 2 3 4))
    (2 4 6 8)
  </code></pre>
  
  <p>I understand that <code>#'</code> denotes a function. So my question is, is it some sort of convention or recommended practice? Can anything go wrong if I don't prefix lambdas with <code>#'</code>, is it implementation dependent?</p>