Why is this assignment not working … it compiles

playground.swift

//: A UIKit based Playground for presenting user interface

//
//  QuizList.swift
//  QuizList
//
//  Created by Alexander v. Below on 09.06.19.
//  Copyright © 2019 None. All rights reserved.
//

import SwiftUI
import PlaygroundSupport

struct QuizListElement: Equatable, Codable {
    var number: Int
    var text: String
}

struct QuizList : Collection, Codable, Equatable {
    typealias Index = Int
    typealias Element = QuizListElement

    init() {
        itemList =  [
            Element(number:  1, text: "Surprise"),
            Element(number:  2, text: "Fear"),
            Element(number:  3, text: "Ruthless efficiency"),
            Element(number:  4, text: "Almost fanatical devotion to the Pope"),
            Element(number:  5, text: "Nice red uniforms"),
        ]
    }

    private let itemList: [Element]

    var startIndex: Int { return itemList.startIndex }
    var endIndex: Int { return itemList.endIndex }

    subscript(position: Int) -> Element {
        return itemList[position]
    }

    func index(after i: Int) -> Int {
        return itemList.index(after: i)
    }

    static func ==(lhs: [Element], rhs: QuizList) -> Bool {
        return lhs == rhs.itemList
    }
}

struct ListView: View {
    var list: QuizList
    @State var quizList = [QuizListElement]()

    internal func reshuffle () {
        var mutableList = [QuizListElement]()
        for element in self.list {
            mutableList.append(element)
        }
        let shuffledList = mutableList.shuffled()
        debugPrint("shuffledList has \(shuffledList.count) elements")
        self.quizList = shuffledList
        debugPrint("quizList has \(quizList.count) elements")
    }

    init(list: QuizList) {
        self.list = list
        reshuffle()
    }

    var body: some View {
        List {
            ForEach (0..<quizList.count) { i in
                Text(quizList[i].text)
            }
            .onMove(perform: move)
        }
    }

    func move(from indices: IndexSet, to newOffset: Int) {
        quizList.move(fromOffsets: indices, toOffset: newOffset)
    }
}

PlaygroundPage.current.setLiveView(ListView(list: QuizList()))