apologies for recommending to extend your scope of interest. But I would highly recommend to add to your list of 'targets': mobile development. That's because you mentioned: longterm.

Longerm, in my views, means being able to write software for web, desktop, multiple smart-phone/table platforms, with a backend in, ideally, the same language/tooling as front end.

It seems like ReasonML is the only one that is targeting the above [1] (but I could be wrong). And that's because of its integration/support of ReactNative.

[1] https://medium.com/@peterpme/your-first-reasonml-pr-into-an-...