title: Why there's no Int Index for Set struct in Swift?
body: <p>I know that Strings in Swift don't have <code>Int</code> indices as Swift supports Grapheme Clusters. But, when coming to Collections in Swift, <code>Array</code> supports <code>Int</code> indices but <code>Set</code> does not support <code>Int</code> indices. What is the reason behind this ?</p>