Use Church Encoding to create objects using only functions

ObjectsFromFunctions.swift

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

import UIKit

// ----------------------------
// Create the "object".
// Basically it's a dispatch table.
typealias Person = (String) -> Any

var PersonInit: ((String, String) -> Person)!
PersonInit = { (firstName: String, lastName: String) -> Person in
    return { method in
        switch method {
        case "firstName":
            return firstName
        case "lastName":
            return lastName
        case "fullName":
            return firstName + " " + lastName
        case "setFirstName":
            return { (newName: String) -> Person in
                return PersonInit(newName, lastName)
            }
        case "setLastName":
            return { (newName: String) -> Person in
                return PersonInit(firstName, newName)
            }
        case "setNames":
            return { newFirstName in
                return { newLastName in
                    return PersonInit(newFirstName, newLastName)
                }
            }
        case _:
            fatalError("Unknown method")
        }
    }
}

// ----------------------------
// Create the "methods"
let firstName = { (person: Person) -> String in
    return person("firstName") as! String
}
let lastName = { (person: Person) -> String in
    return person("lastName") as! String
}
let fullName = { (person: Person) -> String in
    return person("fullName") as! String
}
let setFirstName = { (person: Person) -> ((String) -> Person) in
    return person("setFirstName") as! ((String) -> Person)
}
let setLastName = { (person: Person) -> ((String) -> Person) in
    return person("setLastName") as! ((String) -> Person)
}
let setNames = { (person: Person) -> ((String) -> ((String) -> Person)) in
    return person("setNames") as! ((String) -> ((String) -> Person))
}

// ----------------------------
// Quick test
let papa = PersonInit("Papa", "Smurf")
fullName(papa)  // "Papa Smurf"

let brainy = setFirstName(papa)("Brainy")
fullName(brainy)  // "Brainy Smurf"

// ----------------------------
// Add a dot-like operator.
infix operator =>

func => <T>(lhs: Person, rhs: (Person) -> T) -> T {
    return rhs(lhs)
}
func => <T, A>(lhs: Person, rhs: (((Person) -> (A) -> T), A)) -> T {
    return rhs.0(lhs)(rhs.1)
}
func => <T, A, B>(lhs: Person, rhs: (((Person) -> (A) -> (B) -> T), A, B)) -> T {
    return rhs.0(lhs)(rhs.1)(rhs.2)
}

// ----------------------------
// The result
papa=>firstName  // "Papa"
papa=>lastName   // "Smurf"
papa=>fullName   // "Papa Smurf"

let hefty = papa=>(setFirstName, "Hefty")
hefty=>fullName  // "Hefty Smurf"

let gargamel = hefty=>(setNames, "Gargamel", "the wizard")
gargamel=>fullName  // "Gargamel the wizard"