Building a Snake Game in Jack: Working With a Minimalist OOP Language

Today, I want to share my experience developing a classic Snake game using Jack, a simple object-oriented programming language designed for educational purposes. This journey taught me valuable lessons about both game development and the constraints of working with a minimalist programming language.

The Jack Language: Simple Yet Challenging

Jack is an interesting language that strips away many features taken for granted in modern languages. There's no inheritance, no floating-point numbers, and even basic operators like != are missing. Instead of writing if (x != y), you have to write if (~(x = y)). These limitations forced me to think differently about how I structure my code.

Game Architecture

I divided the game into four main classes:

• Main: The entry point
• Game: The game loop and core logic
• Snake: The snake's behavior and movement
• Food: Food spawning and positioning

The most challenging part was managing the snake's movement. I represented the snake as an array of x,y coordinate pairs, where each pair defines a segment's position. When the snake moves, each segment takes the position of the segment in front of it, and the head moves in the current direction.

Memory Management Matters

One aspect of Jack that really made me appreciate modern languages is manual memory management. Every object you create must be explicitly disposed of when you're done with it. My Game class's dispose method had to clean up both the snake and food objects:

method void dispose() {
    do snake.dispose();
    do food.dispose();
    do Memory.deAlloc(this);
    return;
}

Random Number Generation

Generating random positions for the food was tricky since Jack doesn't have a random number generator. I implemented a simple pseudo-random number generator using the following algorithm:

method void randomize() {
    let seed = seed + 20251;
    let seed = seed * 2377;
    let seed = seed / 7;
    // Use seed to calculate x,y positions
    return;
}

Control Flow Quirks

The lack of else-if statements led to some deeply nested code. For example, handling keyboard input looks like this:

if (key = 131) { // Up
    do snake.changeDirection(1);
} else {
    if (key = 133) { // Down
        do snake.changeDirection(2);
    } else {
        if (key = 130) { // Left
            do snake.changeDirection(3);
        } else {
            if (key = 132) { // Right
                do snake.changeDirection(4);
            }
        }
    }
}

Evidently not the most elegant of soulutions, but it got the job done.

Graphics and Screen Management

The game's visual elements are quite basic - the snake segments are rectangles, and the food is a circle. Jack's Screen class provides basic drawing primitives, but you have to manage everything at the pixel level. The screen is 512x256 pixels, and you need to be careful not to draw outside these boundaries.

Lessons Learned

Building this game taught me several valuable lessons:

1. The importance of careful memory management
2. How to work within the constraints of a limited language
3. The value of breaking down complex problems into smaller, manageable pieces
4. The fundamentals of game loop implementation

Most importantly, it gave me a deeper appreciation for the conveniences we have in modern programming languages. Every feature we take for granted today - garbage collection, rich standard libraries, complex control structures - exists because someone once had to program without it and said "there must be a better way."