enum Space<T> {
    case contains(val:T)
    case empty

    //A mapping from Domain of type T to Codomain of type T
    func function(f:(T) -> T) -> Space{
        switch self {
        case .contains(let x):
            return .contains(val: f(x))
        case .empty:
            return .empty
        }
    }

    //A mapping from Domain of type T to Codomain of type U
    func functor<U>(f:(T) -> U) -> Space<U> {
        switch self {
        case .contains(let x):
            return .contains(val: f(x))
        case .empty:
            return .empty
        }
    }
}

//Example of our functor function
func readMe(_ num:CNumber) -> String{
    switch num {
    case CNumber(a: 0.0, b: 0.0):
        return "Nothing"
    case CNumber(a: 0.0, b: 1.0):
        return "i"
    default:
        return "Not a CNumber"
    }
}


let z1 = Space.contains(val: 1.0.i)
let z2 = z1.functor(f: readMe)