Experiments in typing

Experiment1.swift

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

import UIKit

protocol HasCreatedAtTimestamp {
    var createdAt: Date { get }
    
    func setCreatedAt(date: Date) -> Self
}

struct Address: HasCreatedAtTimestamp {
    let city: String
    let state: String
    let code: String
    let country: String
    let createdAt: Date
    
    init(city: String, state: String, code: String, country: String, createdAt: Date) {
        self.city = city
        self.state = state
        self.code = code
        self.country = country
        self.createdAt = createdAt
    }
    
    func setCreatedAt(date: Date) -> Address {
        return Address(city: city, state: state, code: code, country: country, createdAt: date)
    }
}

struct Person: HasCreatedAtTimestamp {
    let name: String
    let createdAt: Date
    
    init(name: String, createdAt: Date) {
        self.name = name
        self.createdAt = createdAt
    }
    
    func setCreatedAt(date: Date) -> Person {
        return Person(name: name, createdAt: date)
    }
}

extension Array where Element: HasCreatedAtTimestamp {
    func overrideCreateAt(with date: Date) -> Array<Element> {
        return self.map({ (s) -> Element in
            return s.setCreatedAt(date: date)
        })
    }
}

func save(addresses: Array<Address>) {
    let updatedAddresses = addresses.overrideCreateAt(with: Date())
    print(updatedAddresses[0].createdAt)
}

func save(persons: Array<Person>) {
    let updatedPersons = persons.overrideCreateAt(with: Date())
    print(updatedPersons[0].createdAt)
}

let persons = [
    Person(name: "Erin", createdAt: Date(timeIntervalSinceNow: -3600.0)),
    Person(name: "Rudy", createdAt: Date(timeIntervalSinceNow: -7200.0))
]
print(persons[0].createdAt)

save(persons: persons)