I hope not. It is hideous and unnecessary.
Especially with nested expressions, the inability to find mismatched parens and braces ultimately turned my team's experiment with it sour.
The base language's grammar is said to have inconsistencies, but I think Reason's 1:1 matching while keeping older constructs makes translating very difficult. There is a tool to do so, but it's lossy.
That said, I use Reason React for a small front end project at work and sort of wish that the ppx for JSX wasn't tied to Reason, so that vanilla OCaml could be used instead.
An example of lossy translation from Reason -> OCaml:
https://reasonml.github.io/en/try?rrjsx=true&reason=DYUwLgBA...
Doesn't it allow to quickly code something like HyperScript-Helpers?
the explicit_arity being added in. I can't think of other examples at the moment.
Maybe lossy is the wrong word, but the transforms historically had gotchas. PPX and what not. Especially when converting between Reason syntax version upgrades and the more stable OCaml syntax (locked to OCaml 4.2 because of bucklescript).
That doesn't necessarily mean lossy, but just that knowing what refmt will error out on depending on the version of Reason the code was written to target vs. locked down ML.