Function try_set 

pub fn try_set<I, E>(
    predicate: fn(&I) -> Result<bool, E>,
) -> impl Fn(&HashSet<I>) -> Result<bool, E>

Checks if all elements in the HashSet satisfy the predicate (fallible ones accepted).

#[derive(Debug, Valust)]
struct All {
    #[valid(func(try(try_set(|x: &String| x.parse::<i32>().map(|u| u > 1)))))]
    data: HashSet<String>
}

let all = Raw::<All> { data: vec!["1".to_owned(), "2".to_owned(), "3".to_owned()].into_iter().collect() };
let val = All::validate(all);
assert!(val.is_err());
println!("{}", val.unwrap_err().full_stringify());