[andreypopp]

Full type inference, pattern matching with exhaustivity checker, modules, abstract types, ...

But to be honest, it's not very useful to do checklist-style comparisons — writing OCaml/Reason code is a completely different experience.

For me it results in less worry about how my code would sustain under refactorings — this is one of the reasons I feel more productive with it rather than with TypeScript or Flow or (of course!) plain JS. I can start writing code and don't worry about getting everything right upfront — refactorings are cheap.