# Advent of Code 2021

this flake builds a package containing a program for each problem in this years advent of code.

## adding a problem

create a folder in `code/src` for the problem, then add an entry with the following format into `code/aoc2021-programs.cabal`:

```
executable aoc2021-XX
   main-is: Main.hs
   ghc-options: -O2 -Wall
   hs-source-dirs: src/XX
   build-depends: base
   default-language: Haskell2010
```

## building

your choice of:

```
nix shell git+https://git.p7.co.nz/thornAvery/aoc2021
nix build git+https://git.p7.co.nz/thornAvery/aoc2021
```

or you can add the overlay defined in the flake

## running

this flake defines a wrapper script that automates passing input to the problems.

in order to use it, the problem folder must include `XX-input.txt`, where `XX` is the suffix defined in the cabal file.

the default package provides a wrapper `aoc2021`, which when invoked with `aoc2021 XX` will cat the contents of `XX-input.txt` to the program `aoc2021-XX` (as defined in the cabal file).