Lumen

A modern, statically-typed functional programming language.

Lumen is a functional programming language designed for clarity, safety, and expressiveness. It brings modern language features into a simple and concise syntax, making it easy to build robust and maintainable software.

Important

Lumen is a personal project, created primarily for my own professional fulfillment and learning.
The goal is not to create the fastest, safest, or most feature-rich language, but rather to explore language design and interpreter implementation. Please consider it an experimental language.

Features

Lumen is built on a foundation of powerful concepts inspired by languages like Rust, Elm, and F#.

• Static Typing: A strong type system catches errors at compile time, not runtime.
• Immutability by Default: Encourages a functional style and makes code more predictable. Variables are immutable unless explicitly marked with mut.
• Rich Type System: Includes expressive algebraic data types like Records (structs) and Sum Types (tagged unions) for precise data modeling.
• Powerful Pattern Matching: Exhaustively match against Sum Types, arrays, and other structures for safe and readable control flow.
• Traits for Abstraction: Define shared behavior across different types using traits, similar to interfaces.
• First-Class Functions: Use higher-order functions, create closures, and pass functions as arguments.
• Pipe Operator (|>): Chain functions together in a clean, readable, left-to-right flow.
• Result-Based Error Handling: Functions that can fail return a Result<Ok, Err> type, ensuring that errors are handled explicitly.

Getting Started

To run a Lumen program, use the Lumen executable and provide the path to your entry file.

# Execute a file
./bin/lumen examples/1-basics/01-variables-and-types.lu

Example: Hello, World!

// main.lu

let main = () => {
  writeln("Hello, Lumen!");
};

main();

Standard Library

Lumen comes with a useful standard library to handle common tasks, including:

• fs: File system operations.
• net.http: Building HTTP servers.
• json: Parsing and serializing JSON data.
• math: Common mathematical functions.
• string: String manipulation utilities.
• io: Console and system interaction (input/output).
• sqlite: Interaction with SQLite databases.
• datetime: Date and time functions.
• enum: Higher-order functions for processing collections (mainly arrays).

License

This project is licensed under the MIT License. See the LICENSE file for details.