doc/guide/localhost/StandardMLPortability

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  22 <a href="./Home">MLton 20180207</a>
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  26 <h1>StandardMLPortability</h1>
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  31 <div class="paragraph"><p>Technically, SML&#8217;97 as defined in the
  32 <a href="DefinitionOfStandardML">Definition</a>
  33 requires only a minimal initial basis, which, while including the
  34 types <span class="monospaced">int</span>, <span class="monospaced">real</span>, <span class="monospaced">char</span>, and <span class="monospaced">string</span>, need have
  35 no operations on those base types.  Hence, the only observable output
  36 of an SML&#8217;97 program is termination or raising an exception.  Most SML
  37 compilers should agree there, to the degree each agrees with the
  38 Definition.  See <a href="UnresolvedBugs">UnresolvedBugs</a> for MLton&#8217;s very few corner cases.</p></div>
  39 <div class="paragraph"><p>Realistically, a program needs to make use of the
  40 <a href="BasisLibrary">Basis Library</a>.
  41 Within the Basis Library, there are numerous places where the behavior
  42 is implementation dependent.  For a trivial example:</p></div>
  43 <div class="listingblock">
  44 <div class="content"><div class="highlight"><pre><span class="k">val</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">valOf</span><span class="w"> </span><span class="p">(</span><span class="n">Int</span><span class="p">.</span><span class="n">maxInt</span><span class="p">)</span><span class="w"></span>
  45 </pre></div></div></div>
  46 <div class="paragraph"><p>may either raise the <span class="monospaced">Option</span> exception (if
  47 <span class="monospaced">Int.maxInt == NONE</span>) or may terminate normally.  The default
  48 Int/Real/Word sizes are the biggest implementation dependent aspect;
  49 so, one implementation may raise <span class="monospaced">Overflow</span> while another can
  50 accommodate the result.  Also, maximum array and vector lengths are
  51 implementation dependent.  Interfacing with the operating system is a
  52 bit murky, and implementations surely differ in handling of errors
  53 there.</p></div>
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