import Std::Io::{PrintLine, PrintInt};

// Trait (interface) definition
interface Drawable {
    func Draw(self: &Self);
}

// Type that implements the trait
struct Circle {
    radius: int;
}

extend Circle for Drawable {
    func Draw(self: &Circle) {
        PrintLine("Drawing circle");
    }
}

// Generic function with trait bound: T must implement Drawable
func Render<T: Drawable>(obj: T) {
    obj.Draw();
}

func Main() -> int {
    let c: Circle = Circle { radius: 5 };
    Render(c);  // OK: Circle implements Drawable
    return 0;
}