use std::ops::{Add, Mul, Sub};
macro_rules! assert_equal_len {
    ($a:ident, $b:ident,$func:ident,$op:tt) => {
        assert!(
            $a.len() == $b.len(),
            "{:?}: dimension mismatch: ${:?} ${:?} ${:?}",
            stringify!($func),
            ($a.len(),),
            stringify!($op),
            $b.len(),
        )
    };
}
macro_rules! op {
    ($func:ident, $bound:ident, $op:tt, $method:ident ) => {
        fn $func<T: $bound<T, Output = T> + Copy>(xs: &mut Vec<T>, ys: &Vec<T>) {
            assert_equal_len!(xs, ys, $func, $op);
            for (x, y) in xs.iter_mut().zip(ys.iter()) {
                *x = $bound::$method(*x, *y);
            }
        }
    };
}
op!(add_assign, Add, +=, add);
op!(mul_assign, Mul, *=, mul);
op!(sub_assign, Sub, -=, sub);
fn main() {}
mod test {
    use std::iter;
    macro_rules! test {
        ($func:ident, $x:expr, $y:expr, $z:expr   ) => {
            #[test]
            fn $func() {
                for size in 0usize..10 {
                    let mut xs: Vec<_> = iter::repeat($x).take(size).collect();
                    let ys: Vec<_> = iter::repeat($y).take(size).collect();
                    let zs: Vec<_> = iter::repeat($z).take(size).collect();
                    super::$func(&mut xs, &ys);
                    assert_eq!(xs, zs);
                }
            }
        };
    }
    test!(add_assign, 1, 2, 3);
    test!(mul_assign, 1, 2, 2);
    test!(sub_assign, 4, 2, 2);
}