-- Slide 23

data Point = Point Float Float

data Shape = Singularity Point | Circle Float Point | Square Point Point

distance p1 p2 = 
	let (Point a b) = p1 in
		let (Point c d) = p2 in
			sqrt ((a - c) * (a - c) + (b - d) * (b - d))

perimeter sh = case sh of
	Singularity _ -> 0.0
	Circle r _ -> 3.14 * 2 * r
	Square (Point a b) (Point c d) -> 2 * abs (a - c) + 2 * abs (b - d)