santa-lang

A functional, C-like programming language designed for solving Advent of Code puzzles. Read the docs →

Features

• First-class functions and closures with tail-call optimization
• Functional pipelines (|>) and composition (>>)
• Pattern matching with match expressions and guards
• Lazy sequences and infinite ranges (1..)
• Persistent immutable data structures
• Placeholder syntax (_ + 1) for concise lambdas
• Built-in memoization support
• Rich built-in function library for AoC puzzles
• AoC runner with automatic input fetching

Examples

Language Features

// Pattern matching
let fibonacci = |n| match n {
  0 { 0 }
  1 { 1 }
  n { fibonacci(n - 1) + fibonacci(n - 2) }
};

// Pipelines and functional operations
let result = 1..10
  |> filter(|n| n % 2 == 0)
  |> map(_ * 2)
  |> sum;

// Lazy infinite sequences
let evens = 0.. |> filter(|n| n % 2 == 0) |> take(5);

Advent of Code Solution

A complete solution for AoC 2015 Day 1:

input: read("aoc://2015/1")

part_one: {
  input |> fold(0) |floor, direction| {
    if direction == "(" { floor + 1 } else { floor - 1 }
  }
}

part_two: {
  zip(1.., input) |> fold(0) |floor, [index, direction]| {
    let next_floor = if direction == "(" { floor + 1 } else { floor - 1 };
    if next_floor < 0 { break index } else { next_floor }
  }
}

test: {
  input: "()())"
  part_one: -1
  part_two: 5
}

Reindeer

The language has multiple implementations (affectionately called "reindeer") exploring different execution models and technologies.

Codename	Type	Language
Comet	Tree-walking interpreter	Rust
Blitzen	Bytecode VM	Rust
Dasher	LLVM native compiler	Rust
Donner	JVM bytecode compiler	Kotlin
Vixen	Embedded bytecode VM	C
Prancer	Tree-walking interpreter	TypeScript

Tooling

Name	Description	Language
Workbench	Desktop IDE	Tauri/React
Tinsel	Code formatter	Zig