Rhombus

#lang rhombus

def pi = 3.14159265

interface Shape:
  method area() :: Real

class Circle(radius):
  implements Shape
  override area():
    pi * radius * radius

class Rectangle(width, height):
  implements Shape
  nonfinal
  override area():
    width * height

class Square(color):
  extends Rectangle
  constructor(side):
    super(side, side)("blue")

fun describe(s :: Shape):
  match s
  | c :: Circle:
      "Circle with radius " +& c.radius +& " has area " +& c.area()
  | r :: Rectangle:
      "Rectangle " +& r.width +& "x" +& r.height +& " has area " +& r.area()

fun main():
  def shapes = [Circle(5), Rectangle(3, 4), Square(7)]
  for (s in shapes):
    println(describe(s))

main()