std.env — AID Language

API Reference

Every function in the std.env module.

env.load_dotenv()

Reads key=value pairs from a .env file in the current directory and loads them into the environment. Silently skips if the file doesn't exist — perfect for production where vars come from the platform.

env.load_dotenv()  // loads .env if present, no-op otherwise

env.get(key: string) → string

Returns the value of an environment variable, or an empty string if not set. Use for optional configuration with fallback defaults.

app_name := env.get("APP_NAME")     // "" if not set
log_level := env.get("LOG_LEVEL")   // use default if empty

env.require(key: string) → string

Returns the value of an environment variable or panics with a clear error if not set. Use for configuration the app cannot run without.

port := env.require("PORT")              // panics: "Required env var PORT not set"
secret := env.require("JWT_SECRET")      // app won't start without it
db_url := env.require("DATABASE_URL")    // must know where the DB is

env.all() → map

Returns all environment variables as a key-value map. Useful for debugging configuration in development — never expose in production as it includes sensitive values.

all_vars := env.all()
// Returns: {"PATH": "/usr/bin:...", "PORT": "3000", "HOME": "/root", ...}

Complete Example

Config-driven application with required and optional variables.

module main

use std.http
use std.env

fn main() {
    env.load_dotenv()                          // load .env file

    port := env.require("PORT")                // required — panics if missing
    database_url := env.require("DATABASE_URL") // required

    app_name := env.get("APP_NAME")            // optional — "" if not set
    log_level := env.get("LOG_LEVEL")          // optional

    server := http.new(port: 3000)

    server.get("/config") => fn(req) -> Response {
        Response.json({
            app_name: "My App",
            environment: "development",
            port: "3000"
        })
    }

    // Debug endpoint — dev only!
    server.get("/env") => fn(req) -> Response {
        all_vars := env.all()
        Response.json({ variables: all_vars })
    }

    server.start()
}

.env File Format

Standard key=value pairs, one per line.

# .env — local development configuration
PORT=3000
DATABASE_URL=sqlite://app.db

APP_NAME=My AID App
APP_ENV=development
LOG_LEVEL=debug
JWT_SECRET=my-secret-key
API_KEY=sk-abc123

Generated Rust

What the compiler produces for environment operations.

Transpiled Output (simplified)

use dotenvy::dotenv;
use std::env;

// env.load_dotenv()
dotenv().ok();  // .ok() silently ignores missing .env

// env.get("APP_NAME")
let app_name = env::var("APP_NAME").unwrap_or_default();

// env.require("PORT")
let port = env::var("PORT")
    .expect("Required env var PORT not set");

// env.all()
let all_vars: HashMap<String, String> = env::vars().collect();

🌍 std.env