Optional built with Struct 🤪

Maybe.swift

/// Example of using static functions and properties to construct an instance of a type
/// for a struct, similar to how enum uses its cases.
/// Let's call it Maybe.
struct Maybe<Wrapped> {
    private(set) var value: Wrapped!

    var hasValue: Bool {
        value != nil
    }

    private init(_ value: Wrapped!) {
        self.value = value
    }

    func map<T>(_ transform: (Wrapped) -> T) -> Maybe<T> {
        value == nil ? .none : .some(transform(value))
    }

    func apply<T>(_ transform: Maybe<(Wrapped) -> T>) -> Maybe<T> {
        transform.flatMap(map)
    }

    func flatMap<T>(_ transform: (Wrapped) -> Maybe<T>) -> Maybe<T> {
        value == nil ? .none : transform(value)
    }

    static var none: Maybe {
        Maybe(nil)
    }

    static func some(_ value: Wrapped) -> Maybe {
        Maybe(value)
    }
}