You&#x27;re probably thinking of this, rubygems was optimized using a linked list: <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=9195847" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=9195847</a>