func curry<A, B, R>(_ f: @escaping (A, B) -> R) -> (A) -> (B) -> R {
    return { a in
        { b in
            f(a, b)
        }
    }
}

func curry<A, B, C, R>(_ f: @escaping (A, B, C) -> R) -> (A) -> (B) -> (C) -> R {
    return { a in
        { b in
            { c in
                f(a, b, c)
            }
        }
    }
}

struct User {

    static let create = curry(User.init(id:name:))

    let id: Int
    let name: String
    let email: String?

    init(id: Int, name: String, email: String?) {
        self.id = id
        self.name = name
        self.email = email
    }

    init(id: Int, name: String) {
        self.init(id: id, name: name, email: nil)
    }
}

type(of: User.create)