This project uses the Dune build system (which can be installed using the Opam package manager for OCaml). There are some common utils in the lib directory, and the source code for each day's problem is in the bin directory. I put the data files in the data directory but do not check them in here, and I tend to hard-code the filenames in the source files, expecting them to be run from the repo directory.
If you are running them from Emacs using the Merlin-Utop
interface, you may want to check your working directory
with Sys.getcwd () and if you find that it is in the bin
or lib directory, do Sys.chdir ".."
To run day1, for example, you can do:
dune exec day1