https://github.com/eddmann/santa-lang-prancer
Prancer - TypeScript tree-walking interpreter for santa-lang with CLI, Web, and Lambda runtimes
https://github.com/eddmann/santa-lang-prancer
advent-of-code aws-lambda bun cli interpreter nodejs prancer santa-lang tree-walking-interpreter typescript
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Prancer - TypeScript tree-walking interpreter for santa-lang with CLI, Web, and Lambda runtimes
- Host: GitHub
- URL: https://github.com/eddmann/santa-lang-prancer
- Owner: eddmann
- License: mit
- Created: 2022-07-11T17:56:31.000Z (almost 4 years ago)
- Default Branch: main
- Last Pushed: 2026-04-13T16:07:27.000Z (2 months ago)
- Last Synced: 2026-04-13T18:09:42.708Z (2 months ago)
- Topics: advent-of-code, aws-lambda, bun, cli, interpreter, nodejs, prancer, santa-lang, tree-walking-interpreter, typescript
- Language: TypeScript
- Homepage: https://eddmann.com/santa-lang/reindeer/prancer/
- Size: 2.47 MB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Agents: AGENTS.md
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README
# santa-lang Prancer
Tree-walking interpreter implementation of [santa-lang](https://eddmann.com/santa-lang/), written in TypeScript.
## Overview
santa-lang is a functional, expression-oriented programming language designed for solving Advent of Code puzzles. This TypeScript implementation provides a tree-walking interpreter.
Key language features:
- First-class functions and closures with tail-call optimization
- Pipeline and composition operators for expressive data flow
- Persistent immutable data structures
- Lazy sequences and infinite ranges
- Pattern matching with guards
- [Rich built-in function library](https://eddmann.com/santa-lang/builtins/)
- AoC runner with automatic input fetching
Multiple runtime targets are available: CLI and AWS Lambda.
## Architecture
```
Source Code → Lexer → Parser → Evaluator → Result
↓
Environment (Scopes)
```
| Component | Description |
| --------------- | ---------------------------------------------------- |
| **Lexer** | Tokenizes source into keywords, operators, literals |
| **Parser** | Builds an Abstract Syntax Tree (AST) |
| **Evaluator** | Tree-walking interpreter that executes the AST |
| **Environment** | Manages variable bindings and closures across scopes |
For detailed implementation internals, see [ARCHITECTURE.md](docs/ARCHITECTURE.md).
## Installation
### Docker
```bash
docker pull ghcr.io/eddmann/santa-lang-prancer:cli-latest
docker run --rm ghcr.io/eddmann/santa-lang-prancer:cli-latest --help
```
### Release Binaries
Download pre-built binaries from [GitHub Releases](https://github.com/eddmann/santa-lang-prancer/releases):
| Platform | Artifact |
| --------------------- | ---------------------------------------------- |
| Linux (x86_64) | `santa-lang-prancer-cli-{version}-linux-amd64` |
| Linux (ARM64) | `santa-lang-prancer-cli-{version}-linux-arm64` |
| macOS (Intel) | `santa-lang-prancer-cli-{version}-macos-amd64` |
| macOS (Apple Silicon) | `santa-lang-prancer-cli-{version}-macos-arm64` |
### AWS Lambda
Lambda layer available: `santa-lang-prancer-lambda-{version}.zip`
## Usage
```bash
# Run a solution
santa-cli solution.santa
# Run tests defined in a solution
santa-cli -t solution.santa
# Evaluate inline code
santa-cli -e '1 + 2'
# Interactive REPL
santa-cli -r
```
## Example
Here's a complete Advent of Code solution (2015 Day 1):
```santa
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
}
```
Key language features shown:
- **`input:`** / **`part_one:`** / **`part_two:`** - AoC runner sections
- **`|>`** - Pipeline operator (thread value through functions)
- **`fold`** - Reduce with early exit support via `break`
- **`test:`** - Inline test cases with expected values
## Building
Requires [Bun](https://bun.sh/) or use Docker:
```bash
# Install dependencies
make lang/install
make cli/install
# Run tests
make lang/test
make cli/test
# Build CLI binaries
make cli/build
# Build web application
make web/build
# Build Lambda layer
make lambda/build
```
## Development
Run `make help` to see all available targets:
```bash
make help # Show all targets
make shell # Interactive shell in Docker build environment
make lang/test # Run language tests
make cli/test # Run CLI tests
make cli/build # Build CLI binaries
make web/build # Build web application
make lambda/build # Build Lambda layer
```
## Project Structure
```
├── src/
│ ├── lang/ # Core language library
│ │ ├── lexer/ # Tokenization
│ │ ├── parser/ # AST construction
│ │ ├── evaluator/ # Tree-walking interpreter
│ │ └── runner/ # AoC runner support
│ ├── cli/ # Command-line interface
│ ├── web/ # Web application (Next.js)
│ └── lambda/ # AWS Lambda runtime
└── examples/ # Example AoC solutions
```
## Other Reindeer
The language has been implemented multiple times to explore different execution models and technologies.
| Codename | Type | Language |
|----------|------|----------|
| [Comet](https://github.com/eddmann/santa-lang-comet) | Tree-walking interpreter | Rust |
| [Blitzen](https://github.com/eddmann/santa-lang-blitzen) | Bytecode VM | Rust |
| [Dasher](https://github.com/eddmann/santa-lang-dasher) | LLVM native compiler | Rust |
| [Donner](https://github.com/eddmann/santa-lang-donner) | JVM bytecode compiler | Kotlin |
| [Vixen](https://github.com/eddmann/santa-lang-vixen) | Embedded bytecode VM | C |
| [Prancer](https://github.com/eddmann/santa-lang-prancer) | Tree-walking interpreter | TypeScript |
## License
MIT License - see [LICENSE](LICENSE) for details.