As far as my experience, there's little code in Python that I would like to replace with OCaml. Python stuff is research code and small services that were written hastily.
I would love to replace my Go code with OCaml. It was always kind of on the verge though. On one hand, once you use a proper type system, you cannot look at Go. On the other, Go's multicore is just so much better than Async/Lwt. In terms of programming, in terms of debuggability, surely in terms of performance too. Having proper multithreading in 5.0 suddenly makes OCaml strictly superior in my (rather biased) opinion.
I would love to replace my Go code with OCaml. It was always kind of on the verge though. On one hand, once you use a proper type system, you cannot look at Go. On the other, Go's multicore is just so much better than Async/Lwt. In terms of programming, in terms of debuggability, surely in terms of performance too. Having proper multithreading in 5.0 suddenly makes OCaml strictly superior in my (rather biased) opinion.