hashmap with float rust

lala.rs

use std::hash::{Hash, Hasher};
use std::collections::HashMap;

#[derive(Debug, Clone)]
struct Lala {
    a: u32,
    b: f64,
}

impl PartialEq for Lala {
    fn eq(&self, other: &Self) -> bool {
        (self.a == other.a) && (self.b == other.b)
    }
}
impl Eq for Lala {}

impl Hash for Lala {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.a.hash(state);
        unsafe { // ici on converti le float64 en unsigned64 comme si on avait
            // forcé un cast sans modifier son contenu en mémoire
            std::mem::transmute::<f64, u64>(self.b).hash(state);
        }
    }
}

impl Lala {
    pub fn new() -> Self {
        Lala {
            a: 32,
            b: 2.2,
        }
    }
}

fn main() {
    let mut test = HashMap::new();
    let el = Lala::new();

    test.insert(
        el.clone(),
        "caca".to_string(),
    );

    let el = test.get(&el).unwrap();
    println!("{:?}", el);
}