OCaml is an impressive language on many fronts: compile time, speed, memory usage, but then is almost crippled beyond usage by a few unfortunate decisions / (lack of) features:

- Dependency management, despite progress `opam` is hopeless brittle because no one uses lock files, good luck building a project that's more than 3 months old. Additionally, by default everything is installed into a global 'switch' and only one version of each package can exist in it.

- Build tooling: things are finally improving with `dune`, but the amount of packages that are running hyper-complex Makefile based build systems is incredibly frustrating. It can be very difficult to add a dependency or change the layout of these projects if you aren't an expert in arcane Make sigils.

- Error messages: again, finally improving, but the number of times I've gotten errors like "line 78 Syntax Error"... I know that parser generators are appealing academically / intellectually but there's a reason major industrial compilers use recursive descent.

- Documentation: Seemingly non-existent for most packages and the tooling is quite poor compared to peer languages (Haskell, Rust).

- More controversially, I think that modules are a worse solution in practice than typeclasses / traits. The automatic instance resolution coherence brings is a huge ergonomics win, and it also allows for more ecosystem wide collaboration in practice. I know that modular implicits are supposed to bring the 'best of both' but that doesn't even exist yet.

None of the problems above are unfixable but they collaborate to make working in OCaml a very frustrating experience for me, even worse because through them I can see what is actually a quite nice language.

OCaml is one of those languages that has it's own compiler backend. I might have forgotten but I think it even uses it's own linker. It is also backed by organisations, for example people from INRIA university and Jane Street company constantly improve it. I remember it also compiled small programs in a few milliseconds, something LLVM based languages cannot do.

Does it have concurrency or/and asynchronous programming?

OCaml is cool, but have you tried F#?