doc/guide/localhost/MLtonExn

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  22 <a href="./Home">MLton 20180207</a>
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  26 <h1>MLtonExn</h1>
  27 </div>
  28 <div id="content">
  29 <div id="preamble">
  30 <div class="sectionbody">
  31 <div class="listingblock">
  32 <div class="content"><div class="highlight"><pre><span class="k">signature</span><span class="w"> </span><span class="n">MLTON_EXN</span><span class="w"> </span><span class="p">=</span><span class="w"></span>
  33 <span class="w">   </span><span class="k">sig</span><span class="w"></span>
  34 <span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">addExnMessager</span><span class="p">:</span><span class="w"> </span><span class="p">(</span><span class="n">exn</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">string</span><span class="w"> </span><span class="n">option</span><span class="p">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">unit</span><span class="w"></span>
  35 <span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">history</span><span class="p">:</span><span class="w"> </span><span class="n">exn</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">string</span><span class="w"> </span><span class="n">list</span><span class="w"></span>
  36
  37 <span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">defaultTopLevelHandler</span><span class="p">:</span><span class="w"> </span><span class="n">exn</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">&#39;a</span><span class="w"></span>
  38 <span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">getTopLevelHandler</span><span class="p">:</span><span class="w"> </span><span class="n">unit</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="p">(</span><span class="n">exn</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">unit</span><span class="p">)</span><span class="w"></span>
  39 <span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">setTopLevelHandler</span><span class="p">:</span><span class="w"> </span><span class="p">(</span><span class="n">exn</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">unit</span><span class="p">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">unit</span><span class="w"></span>
  40 <span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">topLevelHandler</span><span class="p">:</span><span class="w"> </span><span class="n">exn</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">&#39;a</span><span class="w"></span>
  41 <span class="w">   </span><span class="k">end</span><span class="w"></span>
  42 </pre></div></div></div>
  43 <div class="ulist"><ul>
  44 <li>
  45 <p>
  46 <span class="monospaced">addExnMessager f</span>
  47 </p>
  48 <div class="paragraph"><p>adds <span class="monospaced">f</span> as a pretty-printer to be used by <span class="monospaced">General.exnMessage</span> for
  49 converting exceptions to strings.  Messagers are tried in order from
  50 most recently added to least recently added.</p></div>
  51 </li>
  52 <li>
  53 <p>
  54 <span class="monospaced">history e</span>
  55 </p>
  56 <div class="paragraph"><p>returns call stack at the point that <span class="monospaced">e</span> was first raised.  Each
  57 element of the list is a file position.  The elements are in reverse
  58 chronological order, i.e. the function called last is at the front of
  59 the list.</p></div>
  60 <div class="paragraph"><p><span class="monospaced">history e</span> will return <span class="monospaced">[]</span> unless the program is compiled with
  61 <span class="monospaced">-const 'Exn.keepHistory true'</span>.</p></div>
  62 </li>
  63 <li>
  64 <p>
  65 <span class="monospaced">defaultTopLevelHandler e</span>
  66 </p>
  67 <div class="paragraph"><p>function that behaves as the default top level handler; that is, print
  68 out the unhandled exception message for <span class="monospaced">e</span> and exit.</p></div>
  69 </li>
  70 <li>
  71 <p>
  72 <span class="monospaced">getTopLevelHandler ()</span>
  73 </p>
  74 <div class="paragraph"><p>get the top level handler.</p></div>
  75 </li>
  76 <li>
  77 <p>
  78 <span class="monospaced">setTopLevelHandler f</span>
  79 </p>
  80 <div class="paragraph"><p>set the top level handler to the function <span class="monospaced">f</span>.  The function <span class="monospaced">f</span>
  81 should not raise an exception or return normally.</p></div>
  82 </li>
  83 <li>
  84 <p>
  85 <span class="monospaced">topLevelHandler e</span>
  86 </p>
  87 <div class="paragraph"><p>behaves as if the top level handler received the exception <span class="monospaced">e</span>.</p></div>
  88 </li>
  89 </ul></div>
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