Failed attempt to add shuffle to Rust vec

adding shuffle to vector

pub trait MutableVector<'self, T> {
     fn shuffle(self);
}

impl<'self, T> MutableVector<'self, T> for &'self mut [T] {
    fn shuffle(self) {
        let l=self.len();
        let mut i=l;
        let mut rng = rand::rng();
        loop {
            if i==0 {break;}
            self.swap(i-1,rng.gen_uint_range(0,l));
        i = i -1;
        }
    }
}