Hello World

Let’s write the simplest possible Sage program.

Create a File

Create a file called hello.sg:

agent Main {
    on start {
        print("Hello from Sage!");
        yield(0);
    }
}

run Main;

Run It

sage run hello.sg

Output:

Hello from Sage!
0

What’s Happening?

Let’s break down this program:

1. agent Main { ... } — Declares an agent named Main. Agents are the basic unit of computation in Sage.

2. on start { ... } — The start handler runs when the agent is spawned. Every agent needs at least one handler.

3. print("Hello from Sage!") — Prints a message to the console.

4. yield(0) — Emits a value, signaling that the agent has finished. The emitted value becomes the agent’s result.

5. run Main — Tells the compiler which agent to start. Every Sage program needs exactly one run statement.

Build a Binary

Instead of running directly, you can compile to a standalone binary:

sage build hello.sg -o out/
./out/hello/hello

The binary is self-contained — no Sage installation needed to run it.

Next Steps

Now let’s write something more interesting: Your First Agent.