Hacker News was rewritten in something other than Arc ~2-3 years ago IIRC, and it was only after that that they managed to add a lot of the interesting moderation features.
There are probably better technologies to build an HN clone in today–Clojure seems strictly better than Arc, for instance–the parts of HN that are interesting to copy are the various discussion and moderation features, and my sense of what they are mostly comes from having observed the site and seeing comments here and there over the years.
Hacker News was rewritten in something other than Arc ~2-3 years ago IIRC, and it was only after that that they managed to add a lot of the interesting moderation features.
There are probably better technologies to build an HN clone in today–Clojure seems strictly better than Arc, for instance–the parts of HN that are interesting to copy are the various discussion and moderation features, and my sense of what they are mostly comes from having observed the site and seeing comments here and there over the years.
Here is some alternative code for building an HN clone: https://github.com/jcs/lobsters (see https://lobste.rs/about for differences to HN).