📄 dotenv-mbt: A MoonBit Environment Variable Loader

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dotenv-mbt is a utility library for loading environment variables from .env files in MoonBit applications. Inspired by Rust's dotenvy crate, it provides a simple and efficient way to manage configuration through environment files.

🚀 Key Features

🔄 Environment Loading – Loads variables from .env files into your application
🔍 Variable Substitution – Supports variable substitution in env files
🛠️ Easy to Use – Simple API for quick integration
🔒 Safe – Non-modifying API that doesn't affect the global environment
🌟 MoonBit Native – Designed specifically for the MoonBit language

📥 Installation

moon add ShellWen/dotenv

🚀 Usage Guide for `dotenv-mbt`

dotenv-mbt provides a simple way to load environment variables from files into your MoonBit applications.

📝 What is an Environment File?

An environment file, or env file, is a plain text file consisting of key-value pairs:

.env

HOST=localhost
PORT=3000
DATABASE_URL=mysql://user:pass@localhost/dbname

Common names for env files are .env, .env.dev, .env.prod, but any name can be used. The default path for this library is .env.

🔍 Basic Usage

The simplest way to use dotenv-mbt is with the EnvLoader:

fn main {
  let env_map = @dotenv.EnvLoader::new?().unwrap().load?().unwrap()
  let host = env_map.get("HOST").unwrap()
  println("HOST=\{host}")
}

⚙️ Configuration Options

dotenv-mbt offers several ways to configure the environment loader:

// Load from a specific file path
let loader1 = @dotenv.EnvLoader::from_path?("./.env.dev").unwrap()

// Default loader (equivalent to with_path("./.env"))
let loader2 = @dotenv.EnvLoader::new?().unwrap()

🔄 Variable Access

After loading the environment, you can access variables using the get method:

let env_map = @dotenv.EnvLoader::new?().unwrap().load?().unwrap()

// Get a variable (returns Option)
let host = env_map.get("HOST").unwrap()

// Get with default value if not found
let port = match env_map.get("PORT") {
  Some(p) => p
  None => "8080"
}

// Check if a variable exists
if env_map.get("DATABASE_URL").is_some() {
  // Do something with database URL
}

🔀 Variable Substitution

dotenv-mbt supports variable substitution in env files:

.env

HOST=localhost
URL=http://${HOST}:3000

When loaded, URL will contain http://localhost:3000.

⚠️ Error Handling

dotenv-mbt uses MoonBit's Result type for error handling:

match @dotenv.EnvLoader::new?().unwrap().load?() {
  Ok(env) =>
    // Use environment variables
    println("Loaded successfully")
  Err(e) =>
    // Handle error
    println("Error loading .env file")
}

🛠️ Full Example

fn main {
  // Load environment from .env file
  let env = @dotenv.EnvLoader::new?().unwrap().load?().unwrap()

  // Access variables
  let host = env.get("HOST").unwrap()
  let port = match env.get("PORT") {
    Some(p) => p
    None => "8080"  // Default to 8080 if not set
  }

  // Use variables in your application
  println("Server running at \{host}:\{port}")

  // Check if a variable exists
  if env.get("DEBUG").is_some() {
    println("Debug mode enabled")
  }
}

📦 Project Structure

dotenv-mbt - Core library for loading and parsing environment files.

📚 Inspiration

This project is inspired by dotenvy, a well-maintained fork of the dotenv crate for Rust. While the API and implementation details are adapted for MoonBit, we follow similar principles and parsing rules.

The README of this project is inspired by NyaSearch.

📜 License

This project is licensed under the Apache-2.0 License. See LICENSE for details.

📢 Contact & Support

GitHub Issues: Report an issue

👋 If you like this project, give it a ⭐! Happy coding! 🚀

moonbit-community/dotenv-mbt