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<a href="./Home">MLton 20201002</a>
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<h1>MLtonIntInf</h1>
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<div id="content">
<div id="preamble">
<div class="sectionbody">
<div class="listingblock">
<div class="content"><div class="highlight"><pre><span></span><span class="k">signature</span><span class="w"> </span><span class="n">MLTON_INT_INF</span><span class="w"> </span><span class="p">=</span><span class="w"></span>
<span class="w">   </span><span class="k">sig</span><span class="w"></span>
<span class="w">      </span><span class="k">type</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">IntInf</span><span class="p">.</span><span class="n">int</span><span class="w"></span>

<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">areSmall</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="n">*</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">bool</span><span class="w"></span>
<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">gcd</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="n">*</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">isSmall</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">bool</span><span class="w"></span>

<span class="w">      </span><span class="k">structure</span><span class="w"> </span><span class="n">BigWord</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">WORD</span><span class="w"></span>
<span class="w">      </span><span class="k">structure</span><span class="w"> </span><span class="n">SmallInt</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">INTEGER</span><span class="w"></span>
<span class="w">      </span><span class="k">datatype</span><span class="w"> </span><span class="n">rep</span><span class="w"> </span><span class="p">=</span><span class="w"></span>
<span class="w">         </span><span class="n">Big</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="n">BigWord</span><span class="p">.</span><span class="n">word</span><span class="w"> </span><span class="n">vector</span><span class="w"></span>
<span class="w">       </span><span class="p">|</span><span class="w"> </span><span class="n">Small</span><span class="w"> </span><span class="k">of</span><span class="w"> </span><span class="n">SmallInt</span><span class="p">.</span><span class="n">int</span><span class="w"></span>
<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">rep</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">rep</span><span class="w"></span>
<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">fromRep</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">rep</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="n">option</span><span class="w"></span>
<span class="w">   </span><span class="k">end</span><span class="w"></span>
</pre></div></div></div>
<div class="paragraph"><p>MLton represents an arbitrary precision integer either as an unboxed
word with the bottom bit set to 1 and the top bits representing a
small signed integer, or as a pointer to a vector of words, where the
first word indicates the sign and the rest are the limbs of a
<a href="GMP">GMP</a> big integer.</p></div>
<div class="ulist"><ul>
<li>
<p>
<span class="monospaced">type t</span>
</p>
<div class="paragraph"><p>the same as type <span class="monospaced">IntInf.int</span>.</p></div>
</li>
<li>
<p>
<span class="monospaced">areSmall (a, b)</span>
</p>
<div class="paragraph"><p>returns true iff both <span class="monospaced">a</span> and <span class="monospaced">b</span> are small.</p></div>
</li>
<li>
<p>
<span class="monospaced">gcd (a, b)</span>
</p>
<div class="paragraph"><p>uses <a href="GMP">GMP&#8217;s</a> fast gcd implementation.</p></div>
</li>
<li>
<p>
<span class="monospaced">isSmall a</span>
</p>
<div class="paragraph"><p>returns true iff <span class="monospaced">a</span> is small.</p></div>
</li>
<li>
<p>
<span class="monospaced">BigWord : WORD</span>
</p>
<div class="paragraph"><p>representation of a big <span class="monospaced">IntInf.int</span> as a vector of words; on 32-bit
platforms, <span class="monospaced">BigWord</span> is likely to be equivalent to <span class="monospaced">Word32</span>, and on
64-bit platforms, <span class="monospaced">BigWord</span> is likely to be equivalent to <span class="monospaced">Word64</span>.</p></div>
</li>
<li>
<p>
<span class="monospaced">SmallInt : INTEGER</span>
</p>
<div class="paragraph"><p>representation of a small <span class="monospaced">IntInf.int</span> as a signed integer; on 32-bit
platforms, <span class="monospaced">SmallInt</span> is likely to be equivalent to <span class="monospaced">Int32</span>, and on
64-bit platforms, <span class="monospaced">SmallInt</span> is likely to be equivalent to <span class="monospaced">Int64</span>.</p></div>
</li>
<li>
<p>
<span class="monospaced">datatype rep</span>
</p>
<div class="paragraph"><p>the underlying representation of an <span class="monospaced">IntInf.int</span>.</p></div>
</li>
<li>
<p>
<span class="monospaced">rep i</span>
</p>
<div class="paragraph"><p>returns the underlying representation of <span class="monospaced">i</span>.</p></div>
</li>
<li>
<p>
<span class="monospaced">fromRep r</span>
</p>
<div class="paragraph"><p>converts from the underlying representation back to an <span class="monospaced">IntInf.int</span>.
If <span class="monospaced">fromRep r</span> is given anything besides the valid result of <span class="monospaced">rep i</span>
for some <span class="monospaced">i</span>, this function call will return <span class="monospaced">NONE</span>.</p></div>
</li>
</ul></div>
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