span>.compare x0 x1 <span class="keyword">with</span>
               0 <span class="keywordsign">-&gt;</span> <span class="constructor">Pervasives</span>.compare y0 y1
             <span class="keywordsign">|</span> c <span class="keywordsign">-&gt;</span> c
       <span class="keyword">end</span>

     <span class="keyword">module</span> <span class="constructor">PairsSet</span> = <span class="constructor">Set</span>.<span class="constructor">Make</span>(<span class="constructor">IntPairs</span>)

     <sp