infix operator ??? func ???<T>(lhs: Optional<T>, rhs: String) -> String { return lhs.map(String.init(describing:)) ?? rhs } let a: Int? = 0 print("\(a ??? "empty")") let b: Int? = nil print("\(b ??? "empty")") (edited)infix operator ??? func ???<T>(lhs: Optional<T>, rhs: String) -> String { return lhs.map(String.init(describing:)) ?? rhs } let a: Int? = 0 print("\(a ??? "empty")") let b: Int? = nil print("\(b ??? "empty")") (edited)