Hacker News was written in the Arc lisp dialect, a dialect created by Paul Graham. Arc was implemented on top of Racket, but that has now changed. HN runs on top of SBCL since a few months.But why? For performance reasons. I recently noticed that Hacker News no longer uses paging for long threads. In the past, when a discussion grew large, we had to click “More” to load the next page of comments, and dang would occasionally post helpful tips to remind us about this feature.