Hacker News: The Inside Story of Its Arc Origins, Ranking Algorithm, and Moderation
Hacker News in Uncompromised Detail
A deep dive into Hacker News, from its 2007 launch as Startup News to its current SBCL-based backend. The post explains the site's jargon, voting rules, and the exact front-page ranking formula, including the penalty for text-only posts. It also covers the second-chance pool for overlooked submissions and profiles the moderators, from Paul Graham to dang and tomhow.
The core ranking function (frontpage-rank) from the arc.news codebase was written as: (= gravity* 1.8 timebase* 120 front-threshold* 1 nourl-factor* .4 lightweight-factor* .3 ) (def frontpage-rank (s (o scorefn realscore) (o gravity gravity*)) (* (/ (let base (- (scorefn s) 1) (if (> base 0) (expt base .8) base)) (expt (/ (+ (item-age s) timebase*) 60) gravity)) (if (no (in s!type 'story 'poll)) .5 (blank s!url) nourl-factor* (lightweight s) (min lightweight-factor* (contro-factor s)) (contro-factor s))))