><div>
    <span id="by-predicate"></span>
    <h3>5.3 &nbsp;&nbsp; by predicate</h3>
</div><div><p>Most of the time, predicates are used. They allow selection of any element returning a non-nil value when evaluated against the predicate. Predicates can take the form of functions, keywords or list representation.</p>
</div><div class="code">
    <pre><code class="clojure">(indices ov #(get % :a))   ;; retur indicies where (:a elem) is non-nil

=&gt; [0 1]

(indices ov #(:a %))       ;; more succint function