Hello World

Main Program

Traditionally the first program we write in any programming language is called a Hello World program – a program that simply outputs the text Hello World to the terminal.

Let's write our first program using Ballerina. Use bal run <file_name> to run the samples.

Sample

Run in Playground

//Binds prefix `io` to `ballerina/io` module. 
import ballerina/io;

//The main function is the program entry point.
public function main() {
    // Print text to the console using `io` module `println` function. 
    io:println("Hello World");
}

Output

Hello World

Service

The network constructs in the language make it easy to develop network interactions easily. A simple HTTP service is as follows.

Sample

import ballerina/http;

service / on new http:Listener(9090) {

    // Handles HTTP GET requests.
    resource function get hello() returns string {
        return "Hello World!";
    }

}

Once the above service is started, invoke the service using the cURL command below using another terminal.

curl http://localhost:9090/hello

Output

Hello World!