struct Foobar {
    first: String,
    second: String,
    third: String,
}

fn grab_first(foobar: &Foobar) -> &str {
    &foobar.first
}

fn go<F>(lhs: Foobar, rhs: Foobar, f: F) -> bool
where
    F: Fn(&Foobar) -> &str,
{
    f(&lhs) == f(&rhs)
}

fn main() {
    dbg!(go(
        Foobar {
            first: "alpha".to_owned(),
            second: "beta".to_owned(),
            third: "gamma".to_owned()
        },
        Foobar {
            first: "alpha".to_owned(),
            second: "delta".to_owned(),
            third: "epsilon".to_owned()
        },
        grab_first
    ));
}