Ask HN: What less-popular systems programming language are you using?

Less popular or less commonly used ones. By that, I mean, not including the usual suspects, such as C, C++, Rust and Go (I know the controversy about the last one being a systems programming language or not). I'm asking this because I used C for both application programming and systems programming, early in my career, before I moved to using other languages such as Java and Python. And of late, I've been wanting to get back to doing some systems programming, but preferably in a more modern language (than C) which is meant for that. ... Read full article.