I used to use #OCaml quite a bit, though that was a number of years ago, and I use #Rust a lot now.
One of my main gripes about OCaml is how it wasn't very practical in some ways. There was no way to open a file read/write (very common for, say, databases), and because it lacked things like Haskel's typeclasses or Rust's traits, you'd use different functions to seek on a file opened for input vs. one for output.
Looks like it's still the same.