title: Obtaining a canonical file path
body: <p>In OCaml, how can I obtain a <a href="https://stackoverflow.com/questions/12100299">canonical file path</a>, equivalent to Java's <code>File.getCanonicalPath()</code> (that is, a normalized absolute path)?</p>
  
  <p>Module <code>Filename</code> has a <code>dirname</code> function, but it does not normalize file paths such as <code>/etc/../usr</code> into <code>/usr</code>, for instance.</p>