it's not work until I remove eval_op() and eval(). It's hard to follow

BuildYourOwnLisp/chapter9_s_expressions.html

Lines 333 to 341 in 3cc63eb

    
           <p>If this is successful you should see something like the following when entering input to your program.</p> 
        
           <pre><code data-language='lispy'>lispy&gt; + 2 2 
        
           (+ 2 2) 
        
           lispy&gt; + 2 (* 7 6) (* 2 5) 
        
           (+ 2 (* 7 6) (* 2 5)) 
        
           lispy&gt; *     55     101  (+ 0 0 0) 
        
           (* 55 101 (+ 0 0 0)) 
        
           lispy&gt;</code></pre>

	<p>If this is successful you should see something like the following when entering input to your program.</p>

	<pre><code data-language='lispy'>lispy> + 2 2
	(+ 2 2)
	lispy> + 2 (* 7 6) (* 2 5)
	(+ 2 (* 7 6) (* 2 5))
	lispy> * 55 101 (+ 0 0 0)
	(* 55 101 (+ 0 0 0))
	lispy></code></pre>