Its actually really easy to get involved in hacking on GHC, the main Haskell compiler. Seriously, its as easy as taking some time to just try to build current head and report any build problems! https://ghc.haskell.org/trac/ghc/wiki/Building
I'm actually really excited by all the people starting to jump in and try to learn/help. We've even got 2 really smart high schoolers doing some amazing contributions to GHC recently.
seriously: its easy to get involved in hacking on interesting open source projects. Just choose one you care about and stay excited by, and dig in!
I could be wrong, but I think they're just poking fun at all the "An X interpreter written in Y" where X and Y are the current trendy languages. Usually one of X or Y are JavaScript or Go, so seeing both in the same headline is like some sort of Hacker News headline jackpot.
I'm subscribed to HN's RSS feed using a feed reader app on my phone, and when I saw this item the title was truncated at around "written." Somehow I just knew it would be Go.
I entertained the idea that maybe it would have been written in JavaScript, but I think a JS interpreter written in JS has already been done at least once.