Hacker News Reader

A little bit off-topic, but why is .christmas tld all over hacker news today?

It's a collection of 12 advent calendars (= blogs) by a norwegian agency using the same structure of `*.christmas`: https://bekk.christmas/

And why is the example program written in F#?

Any why are christmas trees green?

Because it's functional.christmas, so everything on it is about functional programming.