Custom Implementations with Protocol Extensions

.swift

import Foundation

protocol Greetable {
    var name: String { get }
    func greet()
}

extension Greetable {
    func greet() {
        print("Hello, \(name)")
    }
}

struct Person: Greetable {
    var name: String
}

let person = Person(name: "Juan")
person.greet()