use std::fmt::Debug;

trait Shape {
    fn area(&self) -> f32;
}

#[derive(Debug)]
struct Square {
    length: i32,
}

impl Square {
    fn new(length: i32) -> Square {
         Square { length }
    }
}

impl Shape for Square {
    fn area(&self) -> f32 {
        (self.length * self.length) as f32
    }
}

#[derive(Debug)]
struct Rectangle {
    width: i32,
    height: i32,
}

impl Rectangle {
    fn new(width: i32, height: i32) -> Rectangle {
         Rectangle { width, height}
    }
}

impl Shape for Rectangle {
    fn area(&self) -> f32 {
        (self.width * self.height) as f32
    }
}

fn print_area<S: Shape+Debug>(shape: &S) {
    println!("The area of {:?} is {}",
        shape,
        shape.area());
}

fn main() {
    let rect = Rectangle::new(30, 50);
    let sqr = Square::new(30);

    print_area(&rect);
    print_area(&sqr);
}