Hello World

Write your first Sounio program

Hello World

Let’s write your first Sounio program.

Creating the File

Create a new file called hello.sio:

fn main() with IO {
    println("Hello, Sounio!")
}

Understanding the Code

  • fn main() - The entry point of every Sounio program
  • with IO - Declares that this function performs IO (recommended; the spec requires explicit effects)
  • println(...) - Outputs a value to the console

Running the Program

souc run hello.sio

Output:

Hello, Sounio!

Adding Variables

fn main() with IO {
    let name = "Sounio"
    let year = 2026

    print("Welcome to ")
    println(name)

    print("Established in ")
    println(year)
}

Next Steps

Now that you’ve written your first program, learn about: