Mutable lazy_static with a Mutex

main.rs

#[macro_use]
extern crate lazy_static;
use std::sync::Mutex;
use std::collections::HashMap;

lazy_static! {
    static ref HASHMAP: Mutex<HashMap<u32, String>> = Mutex::new({
        let mut m = HashMap::new();
        m.insert(0, String::from("foo"));
        m.insert(1, String::from("bar"));
        m.insert(2, String::from("baz"));
        m
    });
}

fn main() {
    let mut map = HASHMAP.lock().unwrap();
    map.insert(3, String::from("fuck"));
    println!("There're {} entries in map\".", map.len());
}