gistfile1.txt

tag a {
    left(int);
    right(bool);
}

fn sabotage(@rec(mutable a foo) x) {
    x.foo = left(0);
}

fn main() {
    auto v = @rec(mutable foo = right(true));
    auto sabot = bind sabotage(v);
    alt (v.foo) {
        case (right(?u)) {
            sabot(1);
            log_err u;
        }
    }
}