yurian's Advent of Code

My Advent of Code solutions in Rust, Go, Elixir, Scala, and Haskell, with a shared toolkit for creating, running, and checking both parts of a puzzle. Solution files stay focused on puzzle logic; each language uses its own idioms and native build tools.

Solutions · Getting started · Developer manual · Editors and IDEs

Solutions

• Year 2025 [Scala].
  • Day 1 [Scala].
    • Part I.
    • Part II.
• Year 2024 [Scala].
  • Day 1 [Scala].
  • Day 2 [Scala].
• Year 2023 [Elixir].
  • Day 1 [Elixir].
• Year 2022 [Rust].
  • Day 1 [Rust].
• Year 2021 [Haskell | Rust | Scala].
  • Day 1 [Scala].
  • Day 2 [Scala].
  • Day 3 [Scala].
  • Day 4 [Haskell].
  • Day 5 [Haskell].
  • Day 6 [Haskell].
  • Day 7 [Rust].
  • Day 8 [Rust].
    • Part I.
    • Part II.
  • Day 9 [Haskell].
• Year 2020 [Elixir | Go].
  • Day 1 [Go].
  • Day 2 [Elixir].

Getting started

Install Nix and direnv, then enable your shell's direnv hook. From the repository root, review .envrc and run direnv allow once to approve it. At the next prompt, a base environment supplies the compiled aoc command, common utilities, and Neovim on PATH. Language commands select their toolchain as needed; entering a language directory also selects its environment after approving that directory's .envrc.

aoc doctor --lang rust
aoc list
aoc test 2022 1 --lang rust --part 2
aoc run 2022 1 --lang rust --part 2 --time
aoc new 2026 1 --lang rust
aoc edit 2026 1 --lang rust
# Implement a part and add its example before running the new day.
aoc watch 2026 1 --lang rust

Without direnv, enter the base environment with nix develop, a language environment with nix develop .#rust, or every toolchain with nix develop .#all. For an existing manual toolchain installation, the root ./aoc launcher remains available and builds the CLI with Cargo. New solutions contain unfinished stubs, never generated puzzle answers.

Run nix develop .#all --command bash ./scripts/check.sh to verify the toolkit and existing inline examples with all five toolchains. No personal puzzle input is needed.

Real puzzle inputs live in ignored data/yYY/dDD/input.txt files. Existing local inputs are retained during migration. Fetch your own input with aoc fetch YEAR DAY after setting AOC_SESSION securely in your environment. Example inputs and typed expected answers live inline in native source or tests. Run one with aoc run YEAR DAY --lang LANG --part 1 --example; stdin, clipboard, and explicit input files are also supported.

• Developer manual: setup, commands, input sources, offline use, timing, benchmarks, and adding a language.
• Writing a solution: shared stream-first processing, native parser libraries, typed examples, and IDE execution.
• Editors and IDEs: project roots, language servers, formatting, run/test tasks, and debugging.
• Design and migration: accepted decisions, data contract, existing solutions, and limitations.

The documentation is maintained as Markdown in this repository; there is no published documentation website yet. The language guides below describe each language's solution shape, example checks, and native commands.

Open advent.code-workspace for optional VS Code integration, or open the language project in your preferred editor. The build metadata is the source of truth; no editor is required.

Language	Project	Build tool	Instructions
Rust	rust/	Cargo; one crate per year	Rust guide
Go	go/	Go modules	Go guide
Elixir	elixir/	Mix tasks, NimbleParsec, and example macros	Elixir guide
Scala	scala/	Scala CLI and Kyo; optional parallelism and streaming	Scala guide
Haskell	haskell/	Cabal	Haskell guide