Swift 2.0 Protocols & Generic Constraints in response to http://inessential.com/2015/07/19/secret_projects_diary_2_swift_2_0_prot

RSSReaderExample.swift

//: Playground - noun: a place where people can play

import Cocoa

protocol Feed: Equatable {
	var url: String {get}
}

func ==<F: Feed>(lhs: F, rhs: F) -> Bool {
    return lhs.url == rhs.url
}

protocol Folder {
    typealias FeedType
	var feeds: [FeedType] {get}
	func addFeeds(feedsToAdd: [FeedType])
}

class LocalFeed: Feed {
	var url: String
	init(url: String) {
		self.url = url
	}
}

class LocalFolder<F: Feed>: Folder {
	var feeds = [F]()
	func addFeeds(feedsToAdd: [F]) {
		for oneFeed in feedsToAdd {
			if !feeds.contains(oneFeed) {
				feeds += [oneFeed]
			}
		}
	}
}

let localFeed = LocalFeed(url: "example.com")
let folder = LocalFolder<LocalFeed>()
folder.addFeeds([localFeed])