I couldn't stop myself from playing with OCaml this evening.
An industrial-strength functional programming language with an emphasis on expressiveness and safety
The compiling of an open source project in C++ took to long which gave me an opportunity to download OCaml and start playing with it.
The installation process was really fast and smooth and is on the same page as Rust.
I do love programming languages from the ML family and have already some experience in F# and Haskell.
Not sure though how much time I will spend on this language, only time will tell.