Arc is on the list, but considering its creator (PG) and the founder of YCombinator and HN (also PG) then maybe not so surprising.
What's the criteria for a language being "obscure?" I consider Erlang an obscure language but I'd bet that most people do not. Does it need to have less than a certain % userbase?
What criteria determines a language being "rediscovered all the time?" One post about that language per month? one per year? I don't remember seeing a front page post about several of those languages for quite some time.
Probably something close to: there doesn't exist a subreddit for the language. But with that in mind, Coq (at least) needs to come off that list. The 6 /r/mumps users might actually more meaningfully support its obscurity.
Im not sure I would call Erlang obscure any more, it has stories that end up on the front page often, with plenty of comments, is being used at a fair number of companies now.
Sure it is not as well known as languages like Java, C, and Python, but there is only a dozen or languages at that point.
Personally (and this is certainly not an absolute way to call this), I would say a language like Erlang and Haskell are fringe languages, where as languages like IO and Self are obscure.
What's the criteria for a language being "obscure?" I consider Erlang an obscure language but I'd bet that most people do not. Does it need to have less than a certain % userbase?
What criteria determines a language being "rediscovered all the time?" One post about that language per month? one per year? I don't remember seeing a front page post about several of those languages for quite some time.