#[derive(Debug)]
enum Shape { Circle { r: f64 }, Rect { w: f64, h: f64 }, Dot }

fn name(s: &Shape) -> &'static str {
    match s {
        Shape::Circle { .. } => "circle",
        Shape::Rect { w, h } => if w == h { "square" } else { "rectangle" },
        _ => "other",
    }
}

fn main() { assert_eq!(name(&Shape::Circle {r:1.0}),"circle");assert_eq!(name(&Shape::Rect {w:2.0,h:2.0}),"square");assert_eq!(name(&Shape::Rect {w:2.0,h:3.0}),"rectangle");assert_eq!(name(&Shape::Dot),"other"); }