Not currently an OCaml user, but it's definitely general-purpose. I don't think OCaml fits into a specific broad niche, although one of the areas where it sees

Not currently an OCaml user, but it's definitely general-purpose. I don't think OCaml fits into a specific broad niche, although one of the areas where it sees more use is in computer language development/research. A whole bunch of compilers are implemented in OCaml (Hack and Flow by Facebook, for example), and then there are tools like Coq, and some static analysis tools (Flow is one, I guess) are also in OCaml. What I think you'll find is that the standard library is quite lacking, as is the availability of third-party libraries. The ecosystem is nowhere close to what it is for languages like Node.js, Ruby — or even Haskell.