Derw[0], an ML-family language that targets TypeScript or JavaScript. The aim is to have a language similar to Elm, but can do interop with TS a lot easier. I'm mostly excited that this will make my TypeScript projects a lot more enjoyable for me to work with.
Roughly, Reason is OCaml, Derw is more like Haskell/Elm. Derw wears the Elm influence proudly, with similar design decisions and goals, and similar standards for tooling. Reason is maybe more appealing to people from JS or OCaml backgrounds, with support for things like JSX. Derw is like Elm: functions and values.