[dependencies]

lazy_static = "1.4.0"

#[macro_use]

extern crate lazy_static;

use std::collections::HashMap;

lazy_static! {

    static ref HASHMAP: HashMap<u32, &'static str> = {

        let mut m = HashMap::new();

        m.insert(0, "foo");

        m.insert(1, "bar");

        m.insert(2, "baz");

        m

    };

    static ref COUNT: usize = HASHMAP.len();

    static ref NUMBER: u32 = times_two(21);

}

fn times_two(n: u32) -> u32 { n * 2 }

pub fn test() {

    println!("The map has {} entries.", *COUNT);

    println!("The entry for `0` is \"{}\".", HASHMAP.get(&0).unwrap());

    println!("A expensive calculation on a static results in: {}.", *NUMBER);

}

The map has 3 entries.

The entry for `0` is "foo".

A expensive calculation on a static results in: 42.