I think this past month has been a bit of an outlier with new languages, such as Avail, being posted. That said, I wouldn't count Idris as one of them - it's been around for a little while now, and in the community of people familiar with purely functional languages, it's probably about as well known as Elm or Agda: If talking to a Haskeller, there's a good chance they've at least heard of it.

Of course, it's all relative - this community does have a good number of early language adopters and people involved in programming language research. At the other end of the spectrum, just a few years ago, I met a Java developer who, at the time, hadn't even heard of C# - I'd imagine he'd've been quite shocked by the languages talked about here.