@otini You would be welcome to join us on mathstodon.xyz - people here are pretty accepting of abstraction. We're still a bit quiet and will probably end up being more about "Recreational maths" and similar, but you can always hunt down and follow others, then migrate if/when you find somewhere more in line with your interests.
@otini There's very little there of the things you mention, but they are genuinely niche in the fediverse. You really need to find people to follow, follow them, and then their toots will turn up on your instance. That will make your instance rich in the sorts of things you want.
The problem is finding people to follow.
functional.cafe is an instance for people interested in functional programming and languages.