Enums

Enums in rust are similar to enums in Typescript. They allow you to define a type by enumerating its possible variants.

Ref - https://doc.rust-lang.org/book/ch06-01-defining-an-enum.html

enum Direction {
    North,
    East,
    South,
    West,
}

fn main() {
    let my_direction = Direction::North;
    let new_direction = my_direction; // No error, because Direction is Copy
    move_around(new_direction);
}

fn move_around(direction: Direction) {
    // implements logic to move a character around
}

Why not simply do the following -

fn main() {
    move_around("north".to_string());
}

fn move_around(direction: String) {
    if direction == "north" {
        println!("Moving North");
    }
}

Because we don’t enforce the 4 variants of directions. So this is much looser than strictly allowing only 4 variants for direction

Enums with values

// Define an enum called Shape
enum Shape {
    Circle(f64),  // Variant with associated data (radius)
    Square(f64),  // Variant with associated data (side length)
    Rectangle(f64, f64),  // Variant with associated data (width, height)
}

// Function to calculate area based on the shape
fn calculate_area(shape: Shape) -> f64 {
    // calculates the area of the shape
    return 0
}

fn main() {
    // Create instances of different shapes
    let circle = Shape::Circle(5.0);
    let square = Shape::Square(4.0);
    let rectangle = Shape::Rectangle(3.0, 6.0);

}

We will be implementing the calcuate_area function in the pattern matching section