&gt; Why just maps? why not sets, with useful set methods ?<p>Having programmed in Go for production a while now, in my experience it&#x27;s rarely necessary. Sometimes a set is needed, but it&#x27;s very simple to just use a map[T]struct{}. And if something like union or intersect is needed it&#x27;s usually less than 20 lines to implement all those operations. Usually that operation is only needed in one instance, and it&#x27;s very quick to write.<p>Would it be faster to have a builtin generic set? Absolutely, but it&#x27;s such a small inconvenience I honestly don&#x27;t care.