I love OCaml, but my biggest pain point is not having something like Cargo. I haven't spent a lot of time with opam since 2.0 came out, so maybe it's better now, but when I used it it felt very much designed around installing packages globally, instead of defining dependencies per-project.
The other issue with the package ecosystem is cross-platform support. While OCaml itself works on windows, opam doesn't (or at least didn't) without a lot of extra work, and it seemed like most packages were designed only for unixish OS's.
There are projects where I've used Rust instead of OCaml, even though I'd have preferred to use OCaml, simply because the infrastructure is so much better and easier to use for Rust.
This is a huge step in making OCaml more approachable. I get the feeling that there are quite a few of these modernizations around, but you have to know about them up front in order to hit the happy path. Would be great if there was some sort of "OCaml Happy Path" repo that laid out all of the right tools to use to be successful right off the bat. Sort of on the subject, Reason would be great but last I checked it utterly neglected its native compilation story--it advertised native compilation but every time I ran into an issue the Reason community would tell me that OCaml support was broken and I should use Node. Excited for the improvements to be sure!
The other issue with the package ecosystem is cross-platform support. While OCaml itself works on windows, opam doesn't (or at least didn't) without a lot of extra work, and it seemed like most packages were designed only for unixish OS's.
There are projects where I've used Rust instead of OCaml, even though I'd have preferred to use OCaml, simply because the infrastructure is so much better and easier to use for Rust.