I'm curious about and interested in janet, definitely keeping an eye on it. The author's last language, fennel, is very very impressive to me as a project.

Its strict adherence to lua's runtime semantics repulses lisp nerds like me at first. But after actually using it in some heavy lua projects, it's incredible how clearly the author understood the practical day-to-day problems with lua and air-dropped in a solution to only and exactly those. It doesn't introduce any extra complexity, perf, or debugging concerns; it runs on any version of lua with no compromises. There are endless lisp purity quagmires to get bogged down in and it completely avoids every single one of them. From a language design standpoint I really think it's an incredible achievement.

I've never used janet and don't particularly have a reason to right now. But who knows maybe I'll find an excuse soon.