Erik L. Arneson is a freelance writer and software developer with WordPress experience. He is located in Portland, Oregon. Jekyll 2026-06-18T15:03:10+00:00 https://arnesonium.com/feeds/math.xml Erik L. Arneson Erik L. Arneson 2014-12-02T22:19:09+00:00 https://arnesonium.com/2014/12/camlprime-now-on-opam <p>My first <a href="http://opam.ocaml.org/" target="_blank">OCaml Package Manager (OPAM)</a> submission has just been accepted. You can now find <a href="http://arnesonium.com/2014/11/prime-number-library-for-ocaml/" title="Prime Number Library for OCaml">Camlprime, a prime number library</a>, on <a href="http://opam.ocaml.org/packages/camlprime/camlprime.0.5/" target="_blank">OPAM here</a>.</p> Erik L. Arneson 2014-11-13T17:08:39+00:00 https://arnesonium.com/2014/11/prime-number-library-for-ocaml <p>A couple of weeks ago, I cleaned up my prime number library for <a href="https://ocaml.org/">OCaml</a>. This library has a number of primality-testing methods in it, but my favorite is the <a href="http://jeremykun.com/2013/06/16/miller-rabin-primality-test/">Miller-Rabin primality test</a>. It’s fast and rather accurate. <!--more--></p> <p>If you’d like to take a look at the library, please check out the <a href="https://github.com/pymander/camlprime">camlprime GitHub page</a>. The library is pretty easy to use. If you download and compile the library, you’ll end up with a toplevel that you can play with.</p> <p>The <code>test.ml</code> file has some examples of how to use the primality tests. However, my favorite thing about this library is that it includes a <a href="https://www.haskell.org/haskellwiki/Lazy_evaluation">lazy list</a> implementation of prime numbers. The following example shows how to set up a lazy list of prime numbers proved using the MR algorithm in the toplevel.</p> <div class="language-ocaml highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="o">#</span> <span class="k">open</span> <span class="nc">Num</span> <span class="p">;;</span> <span class="o">#</span> <span class="k">let</span> <span class="n">prime_list</span> <span class="o">=</span> <span class="nn">Prime</span><span class="p">.</span><span class="n">make</span> <span class="p">(</span><span class="nn">Prime</span><span class="p">.</span><span class="n">miller_rabin</span> <span class="mi">500</span><span class="p">)</span> <span class="p">(</span><span class="n">num_of_int</span> <span class="mi">500</span><span class="p">)</span> <span class="p">;;</span> <span class="k">val</span> <span class="n">prime_list</span> <span class="o">:</span> <span class="nn">Num</span><span class="p">.</span><span class="n">num</span> <span class="nn">LazyList</span><span class="p">.</span><span class="n">t</span> <span class="o">=</span> <span class="nn">LazyList</span><span class="p">.</span><span class="nc">Node</span> <span class="p">(</span><span class="nc">Int</span> <span class="mi">503</span><span class="o">,</span> <span class="o">&lt;</span><span class="k">lazy</span><span class="o">&gt;</span><span class="p">)</span> <span class="o">#</span> <span class="nn">Prime</span><span class="p">.</span><span class="n">nth</span> <span class="n">prime_list</span> <span class="mi">500</span> <span class="p">;;</span> <span class="o">-</span> <span class="o">:</span> <span class="nn">Num</span><span class="p">.</span><span class="n">num</span> <span class="o">=</span> <span class="nc">Int</span> <span class="mi">4363</span> </code></pre></div></div> <p>The library is pretty fast, even for really large numbers. I’ve tested it on 300-digit prime numbers, and I’m sure it will scale to sizes much larger than that.</p> <p>Any thoughts or improvements? Let me know in the comments.</p>