It's called a continuation. Continuations are essentially closures being passed around to represent state (hence "fnid"), check the Wikipedia page on them for a proper, computer sciencey definition. The nature of Lisp really lends itself to continuation-based programming. Sometimes (like on HN) it's used in web applications. In the context of web applications, it's a different approach than, for example, REST/MVC. It…
"The nature of Lisp really lends itself to continuation-based programming." This comes up occasionally on HN. I've never seen anyone say anything positive about it. It seems like a software detail that's unnecessary exposed to users. It doesn't make the site better, it makes it worse.
I disagree, as i look at HN several times a day i like how pages expire. It explicitly tells me that the order has changed. People are WAY too fussy about messages in their UX because we have abstracted UX to such an extent that we expect the same smooth UE independently of function. The internets expectations (and sheepishness) is making all software like that crap you get free with your camera.