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  <title>Module: Lisp</title>
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    <div id="classHeader">
        <table class="header-table">
        <tr class="top-aligned-row">
          <td><strong>Module</strong></td>
          <td class="class-name-in-header">Lisp</td>
        </tr>
        <tr class="top-aligned-row">
            <td><strong>In:</strong></td>
            <td>
                <a href="../files/lib/carat/lisp-format_rb.html">
                lib/carat/lisp-format.rb
                </a>
        <br />
                <a href="../files/lib/carat/lisp_rb.html">
                lib/carat/lisp.rb
                </a>
        <br />
            </td>
        </tr>

        </table>
    </div>
  <!-- banner header -->

  <div id="bodyContent">



  <div id="contextContent">

    <div id="description">
      <h1><a href="Lisp.html">Lisp</a> Mixin</h1>
<p>
This module provides <a href="Lisp.html">Lisp</a>-like functional notation.
With this module it almost possibel to write real <a
href="Lisp.html">Lisp</a> code in Ruby.
</p>
<h2>Example</h2>
<p>
It&#8217;s hardly believable, but the following IS valid ruby code:
</p>
<pre>
  (def accumulate (fun, x, list)
    (if (null? list)
      x
    else
      (accumulate fun, (fun.call x, (car list)), (cdr list))
    end)
  end)
</pre>
<p>
A real programmer can write LISP in any language&#8230; ;)
</p>
<h2>Author(s)</h2>
<ul>
<li>Florian Frank

</li>
<li>Thomas Sawyer

</li>
</ul>
<h2>Legal</h2>
<p>
Based on original work func.rb by Florain Frank. Copyright &#169;2005
Florian Frank &lt;flori@ping.de&gt; Ruby License
</p>
<h2>History</h2>
<ul>
<li>2005.04.12

</li>
</ul>
<p>
** Changed the name of Pair class to <a
href="Lisp/DottedPair.html">DottedPair</a>. ** Added a new method <a
href="Lisp.html#M000432">pair!</a> which converts an array to a <a
href="Lisp/DottedPair.html">DottedPair</a>. ** This is then used in <a
href="Lisp.html#M000425">car</a> and <a href="Lisp.html#M000426">cdr</a> to
automatically convert arrays passed to them. ** Note: There may be other
places that <a href="Lisp.html#M000432">pair!</a> conversion is needed.
</p>

    </div>


   </div>

    <div id="method-list">
      <h3 class="section-bar">Methods</h3>

      <div class="name-list">
      <a href="#M000446">accumulate</a>&nbsp;&nbsp;
      <a href="#M000445">all?</a>&nbsp;&nbsp;
      <a href="#M000436">append</a>&nbsp;&nbsp;
      <a href="#M000443">assoc</a>&nbsp;&nbsp;
      <a href="#M000433">atom?</a>&nbsp;&nbsp;
      <a href="#M000425">car</a>&nbsp;&nbsp;
      <a href="#M000426">cdr</a>&nbsp;&nbsp;
      <a href="#M000423">cons</a>&nbsp;&nbsp;
      <a href="#M000424">consonto</a>&nbsp;&nbsp;
      <a href="#M000457">drop</a>&nbsp;&nbsp;
      <a href="#M000434">equal?</a>&nbsp;&nbsp;
      <a href="#M000444">exists?</a>&nbsp;&nbsp;
      <a href="#M000451">explode</a>&nbsp;&nbsp;
      <a href="#M000442">filter</a>&nbsp;&nbsp;
      <a href="#M000447">foldleft</a>&nbsp;&nbsp;
      <a href="#M000449">foldright</a>&nbsp;&nbsp;
      <a href="#M000422">format</a>&nbsp;&nbsp;
      <a href="#M000452">implode</a>&nbsp;&nbsp;
      <a href="#M000437">length</a>&nbsp;&nbsp;
      <a href="#M000450">link</a>&nbsp;&nbsp;
      <a href="#M000435">list</a>&nbsp;&nbsp;
      <a href="#M000438">map</a>&nbsp;&nbsp;
      <a href="#M000441">member?</a>&nbsp;&nbsp;
      <a href="#M000430">null?</a>&nbsp;&nbsp;
      <a href="#M000432">pair!</a>&nbsp;&nbsp;
      <a href="#M000431">pair?</a>&nbsp;&nbsp;
      <a href="#M000440">pairlis</a>&nbsp;&nbsp;
      <a href="#M000454">prod</a>&nbsp;&nbsp;
      <a href="#M000448">reduce</a>&nbsp;&nbsp;
      <a href="#M000455">reverse</a>&nbsp;&nbsp;
      <a href="#M000427">set</a>&nbsp;&nbsp;
      <a href="#M000428">set_car!</a>&nbsp;&nbsp;
      <a href="#M000429">set_cdr!</a>&nbsp;&nbsp;
      <a href="#M000453">sum</a>&nbsp;&nbsp;
      <a href="#M000456">take</a>&nbsp;&nbsp;
      <a href="#M000439">zip</a>&nbsp;&nbsp;
      </div>
    </div>

  </div>


    <!-- if includes -->

    <div id="section">

    <div id="class-list">
      <h3 class="section-bar">Classes and Modules</h3>

      Module <a href="Lisp/Format.html" class="link">Lisp::Format</a><br />
Class <a href="Lisp/DottedPair.html" class="link">Lisp::DottedPair</a><br />

    </div>

    <div id="constants-list">
      <h3 class="section-bar">Constants</h3>

      <div class="name-list">
        <table summary="Constants">
        <tr class="top-aligned-row context-row">
          <td class="context-item-name">VERSION</td>
          <td>=</td>
          <td class="context-item-value">1.1</td>
        </tr>
        </table>
      </div>
    </div>



      


    <!-- if method_list -->
    <div id="methods">
      <h3 class="section-bar">Public Class methods</h3>

      <div id="method-M000422" class="method-detail">
        <a name="M000422"></a>

        <div class="method-heading">
          <a href="#M000422" class="method-signature">
          <span class="method-name">format</span><span class="method-args">(format, *args)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000422-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000422-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp-format.rb, line 1788</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-constant">Lisp</span>.<span class="ruby-identifier">format</span>(<span class="ruby-identifier">format</span>, <span class="ruby-operator">*</span><span class="ruby-identifier">args</span>)
    <span class="ruby-keyword kw">begin</span> 
      <span class="ruby-identifier">state</span> = <span class="ruby-constant">Format</span><span class="ruby-operator">::</span><span class="ruby-constant">State</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">args</span>, <span class="ruby-constant">Format</span><span class="ruby-operator">::</span><span class="ruby-constant">Output</span>.<span class="ruby-identifier">new</span>)
      <span class="ruby-identifier">formatter</span> = <span class="ruby-constant">Format</span><span class="ruby-operator">::</span><span class="ruby-constant">Formatter</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">format</span>, <span class="ruby-identifier">state</span>)
      <span class="ruby-identifier">formatter</span>.<span class="ruby-identifier">run</span>
    <span class="ruby-keyword kw">rescue</span> =<span class="ruby-operator">&gt;</span> <span class="ruby-identifier">e</span>
      <span class="ruby-identifier">puts</span> <span class="ruby-value str">'Format error: '</span> <span class="ruby-operator">+</span> <span class="ruby-identifier">e</span>.<span class="ruby-identifier">message</span>
      <span class="ruby-identifier">puts</span> <span class="ruby-identifier">format</span>
      <span class="ruby-identifier">puts</span> <span class="ruby-value str">' '</span> <span class="ruby-operator">*</span> (<span class="ruby-identifier">e</span>.<span class="ruby-identifier">pos</span> <span class="ruby-operator">-</span> <span class="ruby-value">1</span>) <span class="ruby-operator">+</span> <span class="ruby-value str">'^'</span> <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">e</span>.<span class="ruby-identifier">respond_to?</span> <span class="ruby-identifier">:pos</span>
      <span class="ruby-identifier">raise</span>
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <h3 class="section-bar">Public Instance methods</h3>

      <div id="method-M000446" class="method-detail">
        <a name="M000446"></a>

        <div class="method-heading">
          <a href="#M000446" class="method-signature">
          <span class="method-name">accumulate</span><span class="method-args">(fun, x, list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000446-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000446-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 276</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">accumulate</span>(<span class="ruby-identifier">fun</span>, <span class="ruby-identifier">x</span>, <span class="ruby-identifier">list</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">list</span>)
      <span class="ruby-identifier">x</span>
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-identifier">accumulate</span>(<span class="ruby-identifier">fun</span>, <span class="ruby-identifier">fun</span>.<span class="ruby-identifier">call</span>(<span class="ruby-identifier">x</span>, <span class="ruby-identifier">car</span>(<span class="ruby-identifier">list</span>)), <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">list</span>))
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000445" class="method-detail">
        <a name="M000445"></a>

        <div class="method-heading">
          <a href="#M000445" class="method-signature">
          <span class="method-name">all?</span><span class="method-args">(pred, list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000445-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000445-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 264</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">all?</span>(<span class="ruby-identifier">pred</span>, <span class="ruby-identifier">list</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">list</span>)
      <span class="ruby-keyword kw">true</span>
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">pred</span>.<span class="ruby-identifier">call</span>(<span class="ruby-identifier">car</span>(<span class="ruby-identifier">list</span>))
        <span class="ruby-identifier">all?</span>(<span class="ruby-identifier">pred</span>, <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">list</span>))
      <span class="ruby-keyword kw">else</span>
        <span class="ruby-keyword kw">false</span>
      <span class="ruby-keyword kw">end</span>
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000436" class="method-detail">
        <a name="M000436"></a>

        <div class="method-heading">
          <a href="#M000436" class="method-signature">
          <span class="method-name">append</span><span class="method-args">(l, m)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000436-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000436-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 181</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">append</span>(<span class="ruby-identifier">l</span>, <span class="ruby-identifier">m</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">l</span>)
      <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">m</span>)
        <span class="ruby-keyword kw">nil</span>
      <span class="ruby-keyword kw">else</span>
        <span class="ruby-identifier">cons</span>(<span class="ruby-identifier">car</span>(<span class="ruby-identifier">m</span>), <span class="ruby-identifier">append</span>(<span class="ruby-identifier">l</span>, <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">m</span>)))
      <span class="ruby-keyword kw">end</span>
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-identifier">cons</span>(<span class="ruby-identifier">car</span>(<span class="ruby-identifier">l</span>), <span class="ruby-identifier">append</span>(<span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">l</span>), <span class="ruby-identifier">m</span>))
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000443" class="method-detail">
        <a name="M000443"></a>

        <div class="method-heading">
          <a href="#M000443" class="method-signature">
          <span class="method-name">assoc</span><span class="method-args">(x, list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000443-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000443-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 247</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">assoc</span>(<span class="ruby-identifier">x</span>, <span class="ruby-identifier">list</span>)
    <span class="ruby-identifier">f</span> = <span class="ruby-identifier">filter</span>(<span class="ruby-identifier">lambda</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">y</span><span class="ruby-operator">|</span> <span class="ruby-identifier">x</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">car</span>(<span class="ruby-identifier">y</span>)}, <span class="ruby-identifier">list</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">f</span>) <span class="ruby-keyword kw">then</span> <span class="ruby-keyword kw">nil</span> <span class="ruby-keyword kw">else</span> <span class="ruby-identifier">car</span>(<span class="ruby-identifier">f</span>) <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000433" class="method-detail">
        <a name="M000433"></a>

        <div class="method-heading">
          <a href="#M000433" class="method-signature">
          <span class="method-name">atom?</span><span class="method-args">(x)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000433-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000433-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 165</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">atom?</span>(<span class="ruby-identifier">x</span>)
    <span class="ruby-keyword kw">not</span> <span class="ruby-identifier">pair?</span>(<span class="ruby-identifier">x</span>) <span class="ruby-operator">||</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">x</span>)
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000425" class="method-detail">
        <a name="M000425"></a>

        <div class="method-heading">
          <a href="#M000425" class="method-signature">
          <span class="method-name">car</span><span class="method-args">(pair)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000425-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000425-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 130</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">car</span>(<span class="ruby-identifier">pair</span>)
    <span class="ruby-identifier">pair</span> = <span class="ruby-identifier">pair!</span>(<span class="ruby-identifier">pair</span>)
    <span class="ruby-identifier">pair</span>.<span class="ruby-identifier">first</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000426" class="method-detail">
        <a name="M000426"></a>

        <div class="method-heading">
          <a href="#M000426" class="method-signature">
          <span class="method-name">cdr</span><span class="method-args">(pair)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000426-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000426-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 135</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">pair</span>)
    <span class="ruby-identifier">pair</span> = <span class="ruby-identifier">pair!</span>(<span class="ruby-identifier">pair</span>)
    <span class="ruby-identifier">pair</span>.<span class="ruby-identifier">second</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000423" class="method-detail">
        <a name="M000423"></a>

        <div class="method-heading">
          <a href="#M000423" class="method-signature">
          <span class="method-name">cons</span><span class="method-args">(car, cdr)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p>
Functional API
</p>
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000423-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000423-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 122</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">cons</span>(<span class="ruby-identifier">car</span>, <span class="ruby-identifier">cdr</span>)
    <span class="ruby-constant">DottedPair</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">car</span>, <span class="ruby-identifier">cdr</span>)
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000424" class="method-detail">
        <a name="M000424"></a>

        <div class="method-heading">
          <a href="#M000424" class="method-signature">
          <span class="method-name">consonto</span><span class="method-args">(cdr, car)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000424-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000424-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 126</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">consonto</span>(<span class="ruby-identifier">cdr</span>, <span class="ruby-identifier">car</span>)
    <span class="ruby-constant">DottedPair</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">car</span>, <span class="ruby-identifier">cdr</span>)
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000457" class="method-detail">
        <a name="M000457"></a>

        <div class="method-heading">
          <a href="#M000457" class="method-signature">
          <span class="method-name">drop</span><span class="method-args">(l, n)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000457-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000457-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 328</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">drop</span>(<span class="ruby-identifier">l</span>, <span class="ruby-identifier">n</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">n</span> <span class="ruby-operator">&gt;</span> <span class="ruby-value">0</span> <span class="ruby-keyword kw">and</span> <span class="ruby-keyword kw">not</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">l</span>)
        <span class="ruby-identifier">drop</span>(<span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">l</span>), <span class="ruby-identifier">n</span> <span class="ruby-operator">-</span> <span class="ruby-value">1</span>)
    <span class="ruby-keyword kw">else</span>
        <span class="ruby-identifier">l</span>
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000434" class="method-detail">
        <a name="M000434"></a>

        <div class="method-heading">
          <a href="#M000434" class="method-signature">
          <span class="method-name">equal?</span><span class="method-args">(l, m)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000434-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000434-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 169</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">equal?</span>(<span class="ruby-identifier">l</span>, <span class="ruby-identifier">m</span>)
    <span class="ruby-identifier">l</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">m</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000444" class="method-detail">
        <a name="M000444"></a>

        <div class="method-heading">
          <a href="#M000444" class="method-signature">
          <span class="method-name">exists?</span><span class="method-args">(pred, list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000444-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000444-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 252</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">exists?</span>(<span class="ruby-identifier">pred</span>, <span class="ruby-identifier">list</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">list</span>)
      <span class="ruby-keyword kw">false</span>
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">pred</span>.<span class="ruby-identifier">call</span>(<span class="ruby-identifier">car</span>(<span class="ruby-identifier">list</span>))
        <span class="ruby-keyword kw">true</span>
      <span class="ruby-keyword kw">else</span>
        <span class="ruby-identifier">exists?</span>(<span class="ruby-identifier">pred</span>, <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">list</span>))
      <span class="ruby-keyword kw">end</span>
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000451" class="method-detail">
        <a name="M000451"></a>

        <div class="method-heading">
          <a href="#M000451" class="method-signature">
          <span class="method-name">explode</span><span class="method-args">(string)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000451-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000451-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 300</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">explode</span>(<span class="ruby-identifier">string</span>)
    <span class="ruby-identifier">list</span>(<span class="ruby-operator">*</span>(<span class="ruby-identifier">string</span>.<span class="ruby-identifier">split</span>(<span class="ruby-regexp re">//</span>)))
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000442" class="method-detail">
        <a name="M000442"></a>

        <div class="method-heading">
          <a href="#M000442" class="method-signature">
          <span class="method-name">filter</span><span class="method-args">(pred, list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000442-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000442-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 235</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">filter</span>(<span class="ruby-identifier">pred</span>, <span class="ruby-identifier">list</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">list</span>)
      <span class="ruby-keyword kw">nil</span>
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">pred</span>.<span class="ruby-identifier">call</span>(<span class="ruby-identifier">car</span>(<span class="ruby-identifier">list</span>))
        <span class="ruby-identifier">cons</span>(<span class="ruby-identifier">car</span>(<span class="ruby-identifier">list</span>), <span class="ruby-identifier">filter</span>(<span class="ruby-identifier">pred</span>, <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">list</span>)))
      <span class="ruby-keyword kw">else</span>
        <span class="ruby-identifier">filter</span>(<span class="ruby-identifier">pred</span>, <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">list</span>))
      <span class="ruby-keyword kw">end</span>
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000447" class="method-detail">
        <a name="M000447"></a>

        <div class="method-heading">
          <span class="method-name">foldleft</span><span class="method-args">(fun, x, list)</span>
        </div>
      
        <div class="method-description">
          <p>
Alias for <a href="Lisp.html#M000446">accumulate</a>
</p>
        </div>
      </div>

      <div id="method-M000449" class="method-detail">
        <a name="M000449"></a>

        <div class="method-heading">
          <span class="method-name">foldright</span><span class="method-args">(fun, x, list)</span>
        </div>
      
        <div class="method-description">
          <p>
Alias for <a href="Lisp.html#M000448">reduce</a>
</p>
        </div>
      </div>

      <div id="method-M000452" class="method-detail">
        <a name="M000452"></a>

        <div class="method-heading">
          <a href="#M000452" class="method-signature">
          <span class="method-name">implode</span><span class="method-args">(list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000452-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000452-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 304</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">implode</span>(<span class="ruby-identifier">list</span>)
    <span class="ruby-identifier">accumulate</span>(<span class="ruby-identifier">lambda</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">x</span>, <span class="ruby-identifier">y</span><span class="ruby-operator">|</span> <span class="ruby-identifier">x</span> <span class="ruby-operator">+</span> <span class="ruby-identifier">y</span> }, <span class="ruby-value str">''</span>, <span class="ruby-identifier">list</span>)
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000437" class="method-detail">
        <a name="M000437"></a>

        <div class="method-heading">
          <a href="#M000437" class="method-signature">
          <span class="method-name">length</span><span class="method-args">(list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000437-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000437-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 193</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">length</span>(<span class="ruby-identifier">list</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">list</span>)
      <span class="ruby-value">0</span>
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-value">1</span> <span class="ruby-operator">+</span> <span class="ruby-identifier">length</span>(<span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">list</span>))
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000450" class="method-detail">
        <a name="M000450"></a>

        <div class="method-heading">
          <a href="#M000450" class="method-signature">
          <span class="method-name">link</span><span class="method-args">(lists)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000450-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000450-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 296</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">link</span>(<span class="ruby-identifier">lists</span>)
    <span class="ruby-identifier">accumulate</span>(<span class="ruby-identifier">lambda</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">x</span>, <span class="ruby-identifier">y</span><span class="ruby-operator">|</span> <span class="ruby-identifier">append</span>(<span class="ruby-identifier">x</span>, <span class="ruby-identifier">y</span>) }, <span class="ruby-keyword kw">nil</span>, <span class="ruby-identifier">lists</span>)
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000435" class="method-detail">
        <a name="M000435"></a>

        <div class="method-heading">
          <a href="#M000435" class="method-signature">
          <span class="method-name">list</span><span class="method-args">(*elms)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000435-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000435-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 173</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">list</span>(<span class="ruby-operator">*</span><span class="ruby-identifier">elms</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">elms</span>.<span class="ruby-identifier">empty?</span>
      <span class="ruby-keyword kw">nil</span>
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-identifier">cons</span>(<span class="ruby-identifier">elms</span>.<span class="ruby-identifier">shift</span>, <span class="ruby-identifier">list</span>(<span class="ruby-operator">*</span><span class="ruby-identifier">elms</span>))
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000438" class="method-detail">
        <a name="M000438"></a>

        <div class="method-heading">
          <a href="#M000438" class="method-signature">
          <span class="method-name">map</span><span class="method-args">(fun, list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000438-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000438-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 201</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">map</span>(<span class="ruby-identifier">fun</span>, <span class="ruby-identifier">list</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">list</span>)
      <span class="ruby-keyword kw">nil</span>
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-identifier">cons</span>(<span class="ruby-identifier">fun</span>.<span class="ruby-identifier">call</span>(<span class="ruby-identifier">car</span>(<span class="ruby-identifier">list</span>)), <span class="ruby-identifier">map</span>(<span class="ruby-identifier">fun</span>, <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">list</span>)))
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000441" class="method-detail">
        <a name="M000441"></a>

        <div class="method-heading">
          <a href="#M000441" class="method-signature">
          <span class="method-name">member?</span><span class="method-args">(x, list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000441-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000441-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 223</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">member?</span>(<span class="ruby-identifier">x</span>, <span class="ruby-identifier">list</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">list</span>)
      <span class="ruby-keyword kw">false</span>
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">x</span> <span class="ruby-operator">==</span> <span class="ruby-identifier">car</span>(<span class="ruby-identifier">list</span>)
        <span class="ruby-keyword kw">true</span>
      <span class="ruby-keyword kw">else</span>
        <span class="ruby-identifier">member?</span>(<span class="ruby-identifier">x</span>, <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">list</span>))
      <span class="ruby-keyword kw">end</span>
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000430" class="method-detail">
        <a name="M000430"></a>

        <div class="method-heading">
          <a href="#M000430" class="method-signature">
          <span class="method-name">null?</span><span class="method-args">(x)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000430-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000430-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 152</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">x</span>)
    <span class="ruby-identifier">x</span> <span class="ruby-operator">==</span> <span class="ruby-keyword kw">nil</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000432" class="method-detail">
        <a name="M000432"></a>

        <div class="method-heading">
          <a href="#M000432" class="method-signature">
          <span class="method-name">pair!</span><span class="method-args">(x)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000432-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000432-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 160</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">pair!</span>(<span class="ruby-identifier">x</span>)
    <span class="ruby-keyword kw">return</span> <span class="ruby-identifier">x</span> <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">pair?</span>(<span class="ruby-identifier">x</span>)
    <span class="ruby-keyword kw">return</span> <span class="ruby-constant">DottedPair</span>[<span class="ruby-operator">*</span><span class="ruby-identifier">x</span>]
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000431" class="method-detail">
        <a name="M000431"></a>

        <div class="method-heading">
          <a href="#M000431" class="method-signature">
          <span class="method-name">pair?</span><span class="method-args">(x)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000431-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000431-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 156</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">pair?</span>(<span class="ruby-identifier">x</span>)
    <span class="ruby-identifier">x</span>.<span class="ruby-identifier">is_a?</span>(<span class="ruby-constant">DottedPair</span>)
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000440" class="method-detail">
        <a name="M000440"></a>

        <div class="method-heading">
          <a href="#M000440" class="method-signature">
          <span class="method-name">pairlis</span><span class="method-args">(l, m)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000440-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000440-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 219</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">pairlis</span>(<span class="ruby-identifier">l</span>, <span class="ruby-identifier">m</span>)
    <span class="ruby-identifier">zip</span>(<span class="ruby-identifier">lambda</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">x</span>, <span class="ruby-identifier">y</span><span class="ruby-operator">|</span> <span class="ruby-identifier">cons</span>(<span class="ruby-identifier">x</span>, <span class="ruby-identifier">y</span>) }, <span class="ruby-identifier">l</span>, <span class="ruby-identifier">m</span>)
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000454" class="method-detail">
        <a name="M000454"></a>

        <div class="method-heading">
          <a href="#M000454" class="method-signature">
          <span class="method-name">prod</span><span class="method-args">(list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000454-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000454-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 312</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">prod</span>(<span class="ruby-identifier">list</span>)
    <span class="ruby-identifier">accumulate</span>(<span class="ruby-identifier">lambda</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">x</span>, <span class="ruby-identifier">y</span><span class="ruby-operator">|</span> <span class="ruby-identifier">x</span> <span class="ruby-operator">*</span> <span class="ruby-identifier">y</span> }, <span class="ruby-value">1</span>, <span class="ruby-identifier">list</span>)
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000448" class="method-detail">
        <a name="M000448"></a>

        <div class="method-heading">
          <a href="#M000448" class="method-signature">
          <span class="method-name">reduce</span><span class="method-args">(fun, x, list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000448-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000448-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 286</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">reduce</span>(<span class="ruby-identifier">fun</span>, <span class="ruby-identifier">x</span>, <span class="ruby-identifier">list</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">list</span>)
      <span class="ruby-identifier">x</span>
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-identifier">fun</span>.<span class="ruby-identifier">call</span>(<span class="ruby-identifier">car</span>(<span class="ruby-identifier">list</span>), <span class="ruby-identifier">reduce</span>(<span class="ruby-identifier">fun</span>, <span class="ruby-identifier">x</span>, <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">list</span>)))
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000455" class="method-detail">
        <a name="M000455"></a>

        <div class="method-heading">
          <a href="#M000455" class="method-signature">
          <span class="method-name">reverse</span><span class="method-args">(lists)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000455-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000455-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 316</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">reverse</span>(<span class="ruby-identifier">lists</span>)
    <span class="ruby-identifier">accumulate</span>(<span class="ruby-identifier">lambda</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">x</span>, <span class="ruby-identifier">y</span><span class="ruby-operator">|</span> <span class="ruby-identifier">consonto</span>(<span class="ruby-identifier">x</span>, <span class="ruby-identifier">y</span>) }, <span class="ruby-keyword kw">nil</span>, <span class="ruby-identifier">lists</span>)
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000427" class="method-detail">
        <a name="M000427"></a>

        <div class="method-heading">
          <a href="#M000427" class="method-signature">
          <span class="method-name">set</span><span class="method-args">(var, val, binding)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000427-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000427-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 140</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">set</span>(<span class="ruby-identifier">var</span>, <span class="ruby-identifier">val</span>, <span class="ruby-identifier">binding</span>)
    <span class="ruby-identifier">eval</span> <span class="ruby-node">&quot;var = #{val}&quot;</span>, <span class="ruby-identifier">binding</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000428" class="method-detail">
        <a name="M000428"></a>

        <div class="method-heading">
          <a href="#M000428" class="method-signature">
          <span class="method-name">set_car!</span><span class="method-args">(pair, val)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000428-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000428-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 144</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">set_car!</span>(<span class="ruby-identifier">pair</span>, <span class="ruby-identifier">val</span>)
    <span class="ruby-identifier">pair</span>.<span class="ruby-identifier">first</span> = <span class="ruby-identifier">val</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000429" class="method-detail">
        <a name="M000429"></a>

        <div class="method-heading">
          <a href="#M000429" class="method-signature">
          <span class="method-name">set_cdr!</span><span class="method-args">(pair, val)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000429-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000429-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 148</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">set_cdr!</span>(<span class="ruby-identifier">pair</span>, <span class="ruby-identifier">val</span>)
    <span class="ruby-identifier">pair</span>.<span class="ruby-identifier">second</span> = <span class="ruby-identifier">val</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000453" class="method-detail">
        <a name="M000453"></a>

        <div class="method-heading">
          <a href="#M000453" class="method-signature">
          <span class="method-name">sum</span><span class="method-args">(list)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000453-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000453-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 308</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">sum</span>(<span class="ruby-identifier">list</span>)
    <span class="ruby-identifier">accumulate</span>(<span class="ruby-identifier">lambda</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">x</span>, <span class="ruby-identifier">y</span><span class="ruby-operator">|</span> <span class="ruby-identifier">x</span> <span class="ruby-operator">+</span> <span class="ruby-identifier">y</span> }, <span class="ruby-value">0</span>, <span class="ruby-identifier">list</span>)
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000456" class="method-detail">
        <a name="M000456"></a>

        <div class="method-heading">
          <a href="#M000456" class="method-signature">
          <span class="method-name">take</span><span class="method-args">(l, n)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000456-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000456-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 320</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">take</span>(<span class="ruby-identifier">l</span>, <span class="ruby-identifier">n</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">n</span> <span class="ruby-operator">&gt;</span> <span class="ruby-value">0</span> <span class="ruby-keyword kw">and</span> <span class="ruby-keyword kw">not</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">l</span>)
      <span class="ruby-identifier">cons</span>(<span class="ruby-identifier">car</span>(<span class="ruby-identifier">l</span>), <span class="ruby-identifier">take</span>(<span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">l</span>), <span class="ruby-identifier">n</span> <span class="ruby-operator">-</span> <span class="ruby-value">1</span>))
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-keyword kw">nil</span>
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>

      <div id="method-M000439" class="method-detail">
        <a name="M000439"></a>

        <div class="method-heading">
          <a href="#M000439" class="method-signature">
          <span class="method-name">zip</span><span class="method-args">(fun, l, m)</span>
          </a>
        </div>
      
        <div class="method-description">
          <p><a class="source-toggle" href="#"
            onclick="toggleCode('M000439-source');return false;">[Source]</a></p>
          <div class="method-source-code" id="M000439-source">
<pre>
<span class="ruby-comment cmt"># File lib/carat/lisp.rb, line 209</span>
  <span class="ruby-keyword kw">def</span> <span class="ruby-identifier">zip</span>(<span class="ruby-identifier">fun</span>, <span class="ruby-identifier">l</span>, <span class="ruby-identifier">m</span>)
    <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">l</span>) <span class="ruby-keyword kw">and</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">m</span>)
      <span class="ruby-keyword kw">nil</span>
    <span class="ruby-keyword kw">elsif</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">l</span>) <span class="ruby-keyword kw">or</span> <span class="ruby-identifier">null?</span>(<span class="ruby-identifier">m</span>)
      <span class="ruby-identifier">raise</span> <span class="ruby-constant">ArgumentError</span>.<span class="ruby-identifier">new</span>(<span class="ruby-value str">&quot;zip with unequal length lists&quot;</span>)
    <span class="ruby-keyword kw">else</span>
      <span class="ruby-identifier">cons</span>(<span class="ruby-identifier">fun</span>.<span class="ruby-identifier">call</span>(<span class="ruby-identifier">car</span>(<span class="ruby-identifier">l</span>), <span class="ruby-identifier">car</span>(<span class="ruby-identifier">m</span>)), <span class="ruby-identifier">zip</span>(<span class="ruby-identifier">fun</span>, <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">l</span>), <span class="ruby-identifier">cdr</span>(<span class="ruby-identifier">m</span>)))
    <span class="ruby-keyword kw">end</span>
  <span class="ruby-keyword kw">end</span>
</pre>
          </div>
        </div>
      </div>


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