Although relatively new, Dune has become the de-facto standard build tool for OCaml. The vast majority of packages on Opam uses Dune now.

Reference for project root file: https://dune.readthedocs.io/en/stable/overview.html?highlight=dune-project#project-layout

Before submitting a PR make sure the following things have been done (and denote this
by checking the relevant checkboxes):

• The commits are consistent with our contribution guidelines
• You've added tests (if possible) to cover your change(s)
• All tests are passing (eldev test)
• The new code is not generating bytecode or M-x checkdoc warnings
• You've updated the changelog (if adding/changing user-visible functionality)
• You've updated the readme (if adding/changing user-visible functionality)

Thanks!