</span> (-@) : <span><span>(<span class="type-var">'a</span>, <span class="type-var">'b</span>)</span> <a href="index.html#type-pointer">pointer</a></span> <span>&#45;&gt;</span> int <span>&#45;&gt;</span> <span><span>(<span class="type-var">'a</span>, <span class="type-var">'b</span>)</span> <a href="index.html#type-pointer">pointer</a></span></code></dt><dt class="spec value" id="val-ptr_diff"><a href="#val-ptr_diff" class="anchor"></a><code><span class="keyword">val</span> ptr_diff : <span><span>(<span