Use opam: https://opam.ocaml.org or https://opam.ocaml.org/doc/Install.html.
Additionally, see: https://ocaml.org/install#linux_mac_bsd and https://ocaml.org/docs/set-up-editor.
It is easy to set up with Emacs, for example. VSCodium has OCaml extension as well.
All you need for the OCaml compiler is opam, it handles all the packages and the compiler.
For your project, use dune: https://dune.readthedocs.io/en/stable/quick-start.html.
Can you be more specific?
(Why the down-vote? He does need to be specific, right? Additionally, my experiences are somehow invalid?)
RUN eval $(opam env) && opam install --yes dune=3.7.0
RUN eval $(opam env) && opam install --yes dune=3.19.1
Additionally, see: https://dune.readthedocs.io/en/stable/tutorials/dune-package....
Anyways, what you could do is:
opam pin add dune 3.7.0
opam install dune
opam pin add dune https://github.com/ocaml/dune/releases/download/3.7.0/dune-3.7.0.tbz RUN eval $(opam env) && opam pin add dune 3.7.0 && opam install --yes dune
[ERROR] Package dune has no known version 3.7.0 in the repositories
And the CI build doesn't use Docker caching, so no shenanigans there.
It shows:
all-versions 1.6.3 1.9.3 1.11.4 2.3.0 2.4.0 2.5.1 2.6.1 2.7.1
2.9.3 3.5.0 3.6.2 3.10.0 3.12.1 3.12.2 3.15.3
3.17.2 3.18.2 3.19.0 3.19.1
Your alternative really is:
$ opam pin add dune https://github.com/ocaml/dune/releases/download/3.7.0/dune-3.7.0.tbz
Just FWIW, maybe it might work the way you wanted it to if you do not update the registry; worth a try. It should be able to fetch the correct tarball.