Generic Extensions.swift

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

import Foundation

protocol MyProtocol {
	var count: UInt {get}
	mutating func increment()
}

struct MyStruct<T: MyProtocol>: MyGenericStructProtocol {
	var t: T
}

protocol MyGenericStructProtocol {
	associatedtype GenericType: MyProtocol
	var t: GenericType { get set }
}

extension Array where Element: MyGenericStructProtocol {
	func doWork() -> [Element.GenericType] {
		return map {
			var incremented = $0.t
			incremented.increment()
			return incremented
		}
	}
}

struct SimpleCounter: MyProtocol {
	var count: UInt
	mutating func increment() { count += 1 }
}

[MyStruct(t: SimpleCounter(count: 5)), MyStruct(t: SimpleCounter(count: 0))].doWork()