lso pass the index to the predicate function.<br>
<b>Since</b> 0.3.4<br>
</div>

<pre><span id="VALfind_idx"><span class="keyword">val</span> find_idx</span> : <code class="type">('a -> bool) -> 'a <a href="Barray_slice.html#TYPEt">t</a> -> (int * 'a) option</code></pre><div class="info ">
<code class="code">find_idx p x</code> returns <code class="code">Some (i,x)</code> where <code class="code">x</code> is the <code class="code">i</code>-th element of <code class="code">l</code>,
    and <code class="code