doc/guide/localhost/Defunctorize

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  26 <h1>Defunctorize</h1>
  27 </div>
  28 <div id="content">
  29 <div id="preamble">
  30 <div class="sectionbody">
  31 <div class="paragraph"><p><a href="Defunctorize">Defunctorize</a> is a translation pass from the <a href="CoreML">CoreML</a>
  32 <a href="IntermediateLanguage">IntermediateLanguage</a> to the <a href="XML">XML</a> <a href="IntermediateLanguage">IntermediateLanguage</a>.</p></div>
  33 </div>
  34 </div>
  35 <div class="sect1">
  36 <h2 id="_description">Description</h2>
  37 <div class="sectionbody">
  38 <div class="paragraph"><p>This pass converts a <a href="CoreML">CoreML</a> program to an <a href="XML">XML</a> program by
  39 performing:</p></div>
  40 <div class="ulist"><ul>
  41 <li>
  42 <p>
  43 linearization
  44 </p>
  45 </li>
  46 <li>
  47 <p>
  48 <a href="MatchCompile">MatchCompile</a>
  49 </p>
  50 </li>
  51 <li>
  52 <p>
  53 polymorphic <span class="monospaced">val</span> dec expansion
  54 </p>
  55 </li>
  56 <li>
  57 <p>
  58 <span class="monospaced">datatype</span> lifting (to the top-level)
  59 </p>
  60 </li>
  61 </ul></div>
  62 </div>
  63 </div>
  64 <div class="sect1">
  65 <h2 id="_implementation">Implementation</h2>
  66 <div class="sectionbody">
  67 <div class="ulist"><ul>
  68 <li>
  69 <p>
  70 <a href="https://github.com/MLton/mlton/blob/master/mlton/defunctorize/defunctorize.sig"><span class="monospaced">defunctorize.sig</span></a>
  71 </p>
  72 </li>
  73 <li>
  74 <p>
  75 <a href="https://github.com/MLton/mlton/blob/master/mlton/defunctorize/defunctorize.fun"><span class="monospaced">defunctorize.fun</span></a>
  76 </p>
  77 </li>
  78 </ul></div>
  79 </div>
  80 </div>
  81 <div class="sect1">
  82 <h2 id="_details_and_notes">Details and Notes</h2>
  83 <div class="sectionbody">
  84 <div class="paragraph"><p>This pass is grossly misnamed and does not perform defunctorization.</p></div>
  85 <div class="sect2">
  86 <h3 id="_datatype_lifting">Datatype Lifting</h3>
  87 <div class="paragraph"><p>This pass moves all <span class="monospaced">datatype</span> declarations to the top level.</p></div>
  88 <div class="paragraph"><p><a href="StandardML">Standard ML</a> <span class="monospaced">datatype</span> declarations can contain type
  89 variables that are not bound in the declaration itself.  For example,
  90 the following program is valid.</p></div>
  91 <div class="listingblock">
  92 <div class="content"><div class="highlight"><pre><span class="k">fun</span><span class="w"> </span><span class="n">&#39;a</span><span class="w"> </span><span class="n">f</span><span class="w"> </span><span class="p">(</span><span class="n">x</span><span class="p">:</span><span class="w"> </span><span class="n">&#39;a</span><span class="p">)</span><span class="w"> </span><span class="p">=</span><span class="w"></span>
  93 <span class="w">   </span><span class="k">let</span><span class="w"></span>
  94 <span class="w">      </span><span class="k">datatype</span><span class="w"> </span><span class="n">&#39;b</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="n">&#39;a</span><span class="w"> </span><span class="n">*</span><span class="w"> </span><span class="n">&#39;b</span><span class="w"></span>
  95 <span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">y</span><span class="p">:</span><span class="w"> </span><span class="n">int</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="p">(</span><span class="n">x</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span><span class="w"></span>
  96 <span class="w">   </span><span class="k">in</span><span class="w"></span>
  97 <span class="w">      </span><span class="mi">13</span><span class="w"></span>
  98 <span class="w">   </span><span class="k">end</span><span class="w"></span>
  99 </pre></div></div></div>
 100 <div class="paragraph"><p>Unfortunately, the <span class="monospaced">datatype</span> declaration can not be immediately moved
 101 to the top level, because that would leave <span class="monospaced">'a</span> free.</p></div>
 102 <div class="listingblock">
 103 <div class="content"><div class="highlight"><pre><span class="k">datatype</span><span class="w"> </span><span class="n">&#39;b</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="n">&#39;a</span><span class="w"> </span><span class="n">*</span><span class="w"> </span><span class="n">&#39;b</span><span class="w"></span>
 104 <span class="k">fun</span><span class="w"> </span><span class="n">&#39;a</span><span class="w"> </span><span class="n">f</span><span class="w"> </span><span class="p">(</span><span class="n">x</span><span class="p">:</span><span class="w"> </span><span class="n">&#39;a</span><span class="p">)</span><span class="w"> </span><span class="p">=</span><span class="w"></span>
 105 <span class="w">   </span><span class="k">let</span><span class="w"></span>
 106 <span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">y</span><span class="p">:</span><span class="w"> </span><span class="n">int</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="p">(</span><span class="n">x</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span><span class="w"></span>
 107 <span class="w">   </span><span class="k">in</span><span class="w"></span>
 108 <span class="w">      </span><span class="mi">13</span><span class="w"></span>
 109 <span class="w">   </span><span class="k">end</span><span class="w"></span>
 110 </pre></div></div></div>
 111 <div class="paragraph"><p>In order to safely move `datatype`s, this pass must close them, as
 112 well as add any free type variables as extra arguments to the type
 113 constructor.  For example, the above program would be translated to
 114 the following.</p></div>
 115 <div class="listingblock">
 116 <div class="content"><div class="highlight"><pre><span class="k">datatype</span><span class="w"> </span><span class="p">(</span><span class="n">&#39;a</span><span class="p">,</span><span class="w"> </span><span class="n">&#39;b</span><span class="p">)</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="n">&#39;a</span><span class="w"> </span><span class="n">*</span><span class="w"> </span><span class="n">&#39;b</span><span class="w"></span>
 117 <span class="k">fun</span><span class="w"> </span><span class="n">&#39;a</span><span class="w"> </span><span class="n">f</span><span class="w"> </span><span class="p">(</span><span class="n">x</span><span class="p">:</span><span class="w"> </span><span class="n">&#39;a</span><span class="p">)</span><span class="w"> </span><span class="p">=</span><span class="w"></span>
 118 <span class="w">   </span><span class="k">let</span><span class="w"></span>
 119 <span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">y</span><span class="p">:</span><span class="w"> </span><span class="p">(</span><span class="n">&#39;a</span><span class="w"> </span><span class="n">*</span><span class="w"> </span><span class="n">int</span><span class="p">)</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">T</span><span class="w"> </span><span class="p">(</span><span class="n">x</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span><span class="w"></span>
 120 <span class="w">   </span><span class="k">in</span><span class="w"></span>
 121 <span class="w">      </span><span class="mi">13</span><span class="w"></span>
 122 <span class="w">   </span><span class="k">end</span><span class="w"></span>
 123 </pre></div></div></div>
 124 </div>
 125 </div>
 126 </div>
 127 <div class="sect1">
 128 <h2 id="_historical_notes">Historical Notes</h2>
 129 <div class="sectionbody">
 130 <div class="paragraph"><p>The <a href="Defunctorize">Defunctorize</a> pass originally eliminated
 131 <a href="StandardML">Standard ML</a> functors by duplicating their body at each
 132 application.  These duties have been adopted by the <a href="Elaborate">Elaborate</a>
 133 pass.</p></div>
 134 </div>
 135 </div>
 136 </div>
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