# Advent of code with OCaml

## Getting started

1. Create a repository using this template
1. Install dependencies via `opam install . --deps-only`
1. Put your session cookie into `.session`
1. (Optional) Put the year into `.year` (e.g. 2022)

## HowTo

For each day, first specify a type `t` for the parsed input, and then
there are 3 functions to implement:

- `input : string -> t`, a function to parse the input into a user specified
    type `t`
- `part1 : t -> unit` and `part2 : t -> unit`, functions to execute both parts

The functor `Day.Make` generates a function `run` to run the pipeline.

```ocaml
    val run : ?only_part1:bool -> ?only_part2:bool -> string -> unit
```

The main executable, `aoc`, can be invoked via

```bash
    dune exec aoc DAY
```

which will invoke the `run` function for that DAY, with input taken from
`inputs` directory.
If no input file is present, then the input file would be downloaded using your
session cookie.

If you want to test your program with the small example for the day, the
easiest way is to put it the `example` in the template file.
The expectation test can be invoked with `dune test`, and updated with `dune
promote`, see more in [dune documentation on expectation
tests](https://dune.readthedocs.io/en/stable/tests.html#inline-expectation-tests).