generics.swift

import Foundation

protocol UnpackedProtocol {

  associatedtype ObjectType
  associatedtype PointType

  var points: [PointType] { get set }

}

struct Box {}
struct Sphere {}

struct Unpacked<Box, CGFloat>: UnpackedProtocol {

  typealias ObjectType = Box
  typealias PointType = CGFloat

  var points: [CGFloat]

}

struct Unpacked<Sphere, Double>: UnpackedProtocol {

  typealias ObjectType = Sphere
  typealias PointType = Double

  var points: [Double]

}