Hello, World!

Chapter Status: ✅ 100% Working (6/6 examples)

Last updated: 2025-08-24
Ruchy version: ruchy 3.169.0

Chapter Status: ✅ 100% Test-Driven (3/3 examples passing)
Ruchy Version: v1.10.0
Testing: All examples verified with make test-ch01

The Problem

Every programming journey begins with “Hello, World!” - your first proof that you can make a computer speak. In Ruchy, this first step is immediate and works exactly as tested.

Test-Driven Examples

Example 1: Basic Hello World

This example is tested in tests/ch01-hello-world/test_01_basic.ruchy:

fun main() {
    println("Hello, World!");
}

Output:

Hello, World!

How to run:

ruchy compile hello.ruchy && ./a.out

Example 2: Multiple Print Statements

This example is tested in tests/ch01-hello-world/test_02_multiple_prints.ruchy:

fun main() {
    println("Hello,");
    println("World!");
}

Output:

Hello,
World!

Example 3: Using Variables

This example is tested in tests/ch01-hello-world/test_03_with_variable.ruchy:

fun main() {
    let greeting = "Hello, World!";
    println(greeting);
}

Output:

Hello, World!

Core Concepts

The println Function

• Built-in function for outputting text
• Takes a string or variable as argument
• Automatically adds a newline after printing
• Works reliably in all tested scenarios

The main Function

• Entry point for Ruchy programs
• Must be defined with fun main() syntax
• All code inside executes when program runs
• Required for compiled programs (not needed in REPL)

String Literals

• Enclosed in double quotes: "text"
• Can be stored in variables
• Can be passed directly to println

Testing Your Code

All examples in this chapter can be verified:

# Test all Chapter 1 examples
make test-ch01

# Test specific example
make test-file FILE=tests/ch01-hello-world/test_01_basic.ruchy

Common Patterns

Pattern 1: Direct Output

println("Your message here");

Pattern 2: Variable Storage

let message = "Your message";
println(message);

Pattern 3: Sequential Output

println("First line");
println("Second line");

Summary

✅ What Works (Test-Verified):

• Basic println with string literals
• Multiple println statements
• Variables storing strings
• The fun main() pattern

⏳ Not Yet Tested (Future Chapters):

• String concatenation
• String interpolation
• Multiple arguments to println
• Special characters and escaping

Exercises

Based on our tested examples, try these variations:

1. Exercise 1: Modify the basic Hello World to print your name
2. Exercise 2: Create a program with three println statements
3. Exercise 3: Store two different greetings in variables and print both

Next Steps

In Chapter 2, we’ll explore variables in more detail, including numbers and arithmetic operations - all verified through test-driven development.

Every example in this chapter has been tested and verified to work with Ruchy v1.10.0