struct Some(value: String) {}

struct None() {}

sumtype Option = Some | None;

pub fun main() ! Io -> Unit {
    printOption!(Some("hello, world!"));
    printOption!(None());
}

fun printOption(option: Option) !Io -> Unit {
    when (option) {
        is Some {
            print!("Some(");
            print!(option.value);
            print!(")\n");
        }
        is None {
            print!("None\n");
        }
    }
}