Simple use of protocols in Swift 5.

Protocols.swift

//
// Simple use of protocols
//

// basic protocol
protocol Info {
    var name: String { get set }
}

struct User: Info {
    var name: String
}

let Josh = User(name: "Josh")
print(Josh.name)     // Josh


// protocol inheritance
protocol Pizza {
    var size: String { get set }
}
protocol Burger {
    var price: Double { get set }
}

protocol Merge: Pizza, Burger { }

struct Order: Merge {
    var size: String
    var price: Double
}

let burger = Order(size: "big", price: 4.99)
print(burger.size, burger.price)     // big 4.99