cutils literal notranslate"><span class="pre">dif</span></code> object provides a portable abstraction over how the
<code class="docutils literal notranslate"><span class="pre">dif/2</span></code> predicate is made available by the supported backend Prolog
systems that implement it (B-Prolog, ECLiPSe, XVM, SICStus Prolog,
SWI-Prolog, Trealla Prolog, XSB, and YAP).</p>
<p>Calls to the library predicates are inlined when compiled with the
<code class="docutils literal notranslate"><span class="pre">optimize</