Foo.swift

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

import UIKit

var str = "Hello, playground"

struct Foo {
    private(set) var bar: String
    let baz: String
    
    mutating func updateWith(bar: String) {
        self.bar = bar
    }
    
    mutating func updateAfter(bar: String) -> () -> Foo {
        return {
            // Seems like self here is a copy, even though I thought closures capture by reference? Is there anyway to have self here be a reference so that the 'original' gets updated, without making Foo a class?
            self.bar = bar
            return self
        }
    }
}

var i = Foo(bar: "a", baz: "cat")
print(i) // "Foo(bar: "a", baz: "cat")

i.updateWith("b")
print(i) // "Foo(bar: "b", baz: "cat")

let j = i.updateAfter("c")
print(i) // "Foo(bar: "b", baz: "cat")
i = j()
print(i) // "Foo(bar: "c", baz: "cat")