struct Pair {
    u64: first
    u64: second
impl:
    fn Pair.new(u64 u64)    -> [Pair] cast(Pair)
    fn Pair.first(Pair: p)  -> [u64]  p::first
    fn Pair.second(Pair: p) -> [u64]  p::second
    fn Pair.split(Pair: p)  -> [u64 u64] { p::first p::second }
}

enum Colour { Red Green Blue }

union StrOrU64 {
    u64: number
    Str: string
}

fn main() {
    // Uncomment the next line to see the error
    //1 2 cast(Pair)
    1 2 Pair.new as [pair]
    // Uncomment these lines to see the error
    //pair::first  println
    //pair::second println

    "first:  " print pair Pair.first println
    "second: " print pair Pair.second println
    pair Pair.split
    "second: " print println
    "first:  " print println

    "Red and green the same colour: " print
    Colour::Red Colour::Green == println

    "Hello World" cast(StrOrU64) as [str_union]
    12345         cast(StrOrU64) as [num_union]
    str_union::string println
    str_union::number println // This is dangerous!
    // num_union::string println // This is dangerous and unpredicatable!
    num_union::number println 
    

}