Your First Program¶

Let's write a complete CacaoLang program from scratch and explore the fundamentals.

Hello World¶

Create a file named hello.choco:

print "Hello, World!";

Run it:

./choco hello.choco

Output:

Hello, World!

That's it! Every CacaoLang program is just a series of statements.

Adding Variables¶

Let's make it more interesting by adding variables:

// Variables hold data
let name = "Alice";
let age = 25;

print "Hello, #{name}!";
print "You are #{age} years old.";

Output:

Hello, Alice!
You are 25 years old.

Interactive Program¶

Let's create an interactive program that asks for user input:

// greeting.choco
print "=== Greeting Program ===";
print "";

// Get user's name
let name = input("What is your name? ");

// Get user's age
let age_str = input("How old are you? ");
let age = int(age_str);

// Greet the user
print "";
print "Nice to meet you, #{name}!";

// Determine if adult or minor
if age >= 18 {
    print "You are an adult.";
} else {
    print "You are a minor.";
}

// Calculate birth year (approximately)
let current_year = 2026;
let birth_year = current_year - age;
print "You were born around #{birth_year}.";

Run it:

./choco greeting.choco

Example interaction:

=== Greeting Program ===

What is your name? Bob
How old are you? 30

Nice to meet you, Bob!
You are an adult.
You were born around 1996.

Number Guessing Game¶

Let's build a simple game:

// guess.choco
print "=== Number Guessing Game ===";
print "";

// Generate random number between 1 and 100
let secret = random_int(1, 100);
let attempts = 0;
let guessed = false;

print "I'm thinking of a number between 1 and 100.";
print "";

// Game loop
while guessed == false {
    let guess_str = input("Your guess: ");
    let guess = int(guess_str);
    attempts = attempts + 1;

    if guess < secret {
        print "Too low! Try again.";
    } else {
        if guess > secret {
            print "Too high! Try again.";
        } else {
            guessed = true;
        }
    }
}

print "";
print "Correct! You guessed it in #{attempts} attempts!";
print "The number was #{secret}.";

Working with Functions¶

Let's create a temperature converter:

// temperature.choco

// Function to convert Celsius to Fahrenheit
fn celsius_to_fahrenheit(celsius) {
    let fahrenheit = (celsius * 9 / 5) + 32;
    return fahrenheit;
}

// Function to convert Fahrenheit to Celsius
fn fahrenheit_to_celsius(fahrenheit) {
    let celsius = (fahrenheit - 32) * 5 / 9;
    return celsius;
}

print "=== Temperature Converter ===";
print "";
print "1. Celsius to Fahrenheit";
print "2. Fahrenheit to Celsius";
print "";

let choice_str = input("Choose option (1 or 2): ");
let choice = int(choice_str);

if choice == 1 {
    let temp_str = input("Enter temperature in Celsius: ");
    let celsius = float(temp_str);
    let fahrenheit = celsius_to_fahrenheit(celsius);
    print "#{celsius}°C = #{fahrenheit}°F";
} else {
    if choice == 2 {
        let temp_str = input("Enter temperature in Fahrenheit: ");
        let fahrenheit = float(temp_str);
        let celsius = fahrenheit_to_celsius(fahrenheit);
        print "#{fahrenheit}°F = #{celsius}°C";
    } else {
        print "Invalid choice!";
    }
}

Simple Todo List¶

A console-based todo list:

// todo.choco

let todos = [];
let running = true;

fn show_menu() {
    print "";
    print "=== Todo List ===";
    print "1. Add todo";
    print "2. View todos";
    print "3. Exit";
    print "";
}

fn add_todo() {
    let task = input("Enter task: ");
    todos = push(todos, task);
    print "Added: #{task}";
}

fn view_todos() {
    print "";
    let count = len(todos);

    if count == 0 {
        print "No todos yet!";
    } else {
        print "Your todos:";
        for i in 0..count {
            let num = i + 1;
            let task = todos[i];
            print "#{num}. #{task}";
        }
    }
}

// Main loop
while running == true {
    show_menu();
    let choice_str = input("Choose: ");
    let choice = int(choice_str);

    if choice == 1 {
        add_todo();
    } else {
        if choice == 2 {
            view_todos();
        } else {
            if choice == 3 {
                running = false;
                print "Goodbye!";
            } else {
                print "Invalid choice!";
            }
        }
    }
}

File Processing¶

Reading and writing files:

// notes.choco

print "=== Simple Notes App ===";
print "";

let filename = "notes.txt";

// Check if notes file exists
if file_exists(filename) == true {
    print "Current notes:";
    print "-------------";
    let content = read_file(filename);
    print content;
    print "-------------";
    print "";
}

let action = input("Add note or clear all? (add/clear): ");

if action == "add" {
    let note = input("Enter your note: ");
    append_file(filename, note);
    append_file(filename, "\n");
    print "Note saved!";
} else {
    if action == "clear" {
        write_file(filename, "");
        print "All notes cleared!";
    } else {
        print "No action taken.";
    }
}

Best Practices¶

1. Use Comments¶

// This is a single-line comment
// Explain what your code does

let name = "Alice";  // Variable to store user's name

2. Use Meaningful Names¶

// Good
let user_age = 25;
let total_score = 100;

// Avoid
let x = 25;
let a = 100;

3. Keep Functions Small¶

// Good - single responsibility
fn calculate_total(price, quantity) {
    return price * quantity;
}

fn apply_discount(total, discount_percent) {
    return total * (1 - discount_percent / 100);
}

4. Handle Errors¶

let age_str = input("Enter age: ");
let age = int(age_str);

if age < 0 {
    print "Error: Age cannot be negative!";
} else {
    print "Age: #{age}";
}

5. Use String Interpolation¶

// Good
let message = "Hello, #{name}! You are #{age} years old.";

// Avoid concatenation when interpolation works better
let message = "Hello, " + name + "! You are " + str(age) + " years old.";

Program Structure¶

A well-organized program:

// calculator.choco

// ===== FUNCTIONS =====

fn add(a, b) {
    return a + b;
}

fn subtract(a, b) {
    return a - b;
}

fn multiply(a, b) {
    return a * b;
}

fn divide(a, b) {
    if b == 0 {
        print "Error: Division by zero!";
        return 0;
    }
    return a / b;
}

// ===== MAIN PROGRAM =====

print "=== Simple Calculator ===";
print "";

let num1_str = input("Enter first number: ");
let num1 = float(num1_str);

let operation = input("Enter operation (+, -, *, /): ");

let num2_str = input("Enter second number: ");
let num2 = float(num2_str);

let result = 0;

if operation == "+" {
    result = add(num1, num2);
} else {
    if operation == "-" {
        result = subtract(num1, num2);
    } else {
        if operation == "*" {
            result = multiply(num1, num2);
        } else {
            if operation == "/" {
                result = divide(num1, num2);
            } else {
                print "Invalid operation!";
            }
        }
    }
}

print "";
print "Result: #{result}";

Next Steps¶

Now that you've written your first programs:

Learn more about data types
Explore control flow
Master functions
Try GUI development