Phil Eaton has a subreddit and Discord dedicated to DB implementation and parsers! https://eatonphil.com/discord.html

Great question, I am wondering what other mediums anyone else is using, e.g., irc, slack, niche-topic discord, or weekly zooms. I have had taste of all of these, but I am yet to find something I can think completely satisfies. I know some local area hacker groups have slacks (but anyone can join them), and open-source projects or particularly niche projects have active discord servers/their own forums. Tbf, I mainly browse or lurk most places, or use HN for shitposting so I am not that well-versed.

Edit to add: you may also find that some mastodon servers are particularly suited for some topic you're interested in.

Usenet used to be that. I'd be interested as well. For specific areas, you might be able to find a mailing list (often in the academic sphere). For PL/type theory there's http://lambda-the-ultimate.org/forum/1.

I found that if you follow a bunch of people on twitter who specialize in a niche topic you'll see a lot of casual interesting conversations there

But the problem is that you can't start new discussions or ask a question unless those people follow you back because no one will see/reply to your tweets

Why not start such a space online?

IMHO chat is best for this. E.g. Slack or Discord. Or if you prefer open source solutions then Matrix, IRC, Mattermost or Zulip.

You will need a critical mass, so I would try to aim for around 400-800 members or so. (Usually most people lurk so I wouldn’t aim for a too low number.)

Best of luck!

Any forum frequented by the hackers whose existence non-hackers have yet to discover. Mailing lists seem to be a good example: they're hard enough to use that non-hackers are filtered out. I'm a programmer and I was nearly filtered out myself.

How is HN "semi poor" but you seem to imply Reddit would be good if it weren't service level?

This is what friends are for.

School?