🎄 Advent of Code 2015 — in Elixir

“Ho-ho-hold my pipe operator.”

I decided to tackle the classic Advent of Code 2015 with a language that treats tuples like royalty, pattern-matches in its sleep, and runs on the indestructible BEAM: Elixir. It’s functional, succinct, expressive, and—most importantly—makes me feel clever every time I write |>.

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✨ Why Elixir?

• Functional playground (recursion everywhere, side-effects nowhere).
• Powered by Erlang/OTP — battle-tested for distributed systems and networking.
• mix for painless build & test tooling, iex for REPL happiness.
• Pipes (|>) that turn data flow into poetry.

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🧰 Environment

Erlang/OTP 27 [erts-15.2.7] [64-bit] [smp:8:8] [jit]
Elixir 1.18.3 (compiled with Erlang/OTP 27)

Any recent Elixir ≥ 1.18 plus OTP 27 should work fine.

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📁 Project Layout

.
├── lib/                # One module per day (Day01, Day02…)
├── priv/inputs/        # My puzzle inputs (yours will differ)
├── stories/            # AI-generated dramatic summaries
├── test/               # Asserted examples straight from AoC
└── mix.exs             # Project configuration

Each day’s module contains part1/0, part1/1, part2/0, part2/1:

iex> AOC2015.Day01.part1()
232  # => Santa’s final floor

iex> AOC2015.Day01.part2()
1783 # => First position that hits the basement

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🧪 Running Tests

Tests mirror the official examples—nothing fancy, just green or red:

mix test

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📜 Inputs

Puzzle inputs live in priv/inputs/dayXX.txt.
Advent of Code gives each participant a unique file, so swap in yours if you’re comparing answers.

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📚 AI Story Time

Because elves deserve fan-fiction, every solved day gets an AI-generated, bite-sized, mildly poetic recap in stories/. Imagine Santa starring in a Shakespearian ankle-deep snowdrift.

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📝 My Post-Mortem on Elixir

Elixir is beautiful — succinct, expressive, and reads almost like pseudocode when you get into the flow with Enum, map, and |>. The language encourages good habits: pure functions, clear flow, and testable components. Task.async/await and pattern matching made parallelism and control flow feel natural, not scary.

That said, I’ve only scratched the surface. Advent of Code taught me a lot about Elixir's syntax and idioms, but the real power lies deeper — in the BEAM VM, distributed systems, and the concurrent magic Elixir is known for.

Elixir doesn’t make implementing things easier — quite the opposite sometimes — but once it works, and you’ve got full test coverage, you can sleep well knowing it won’t break randomly.

Would I recommend Elixir for AoC or competitive programming? Probably not. But if you want to learn Elixir, then doing something like AoC is a great playground. You'll pick up real intuition fast. The ecosystem (mix, docs, tests) supports that kind of exploration really well.

At the end of the day, Elixir is a functional language that encourages immutability, composability, and clean code. It won’t solve the problem for you — but it’ll make you feel clever solving it.

For deeper thoughts, odd bugs, and Elixir lessons learned, see MEMO.md.

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❌ License

Unlicense — public domain. Copy it, fork it, tattoo it on a reindeer.

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Thanks for dropping by. May your recursion always find a base case, and may the pipes be ever in your favour. 🌟

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