I'm not sure I prefer 'in' over semicolon in declarations. I mean: let x = ref 0 in (* something *) in Ocaml is not much worse/better than let mu

I'm not sure I prefer 'in' over semicolon in declarations. I mean: let x = ref 0 in (* something *) in Ocaml is not much worse/better than let mut x = 0; // something in Rust. As I said above, that's really a minor, stylistic issue, one probably would write "let x = mut 0 in" for a week or so (coming from OCaml) and that's it, after a week it becomes as natural to write semicolon as it is to write 'in'.