Code shared from the Rust Playground

playground.rs

use std::borrow::Cow;
use std::collections::HashMap;

#[derive(Eq, PartialEq, Hash, Clone, Default, Debug)]
struct Symbol<'a> {
    ns: Cow<'a, str>,
    name: Cow<'a, str>,
}

impl<'a> Symbol<'a> {
    fn new(ns: &'a str, name: &'a str) -> Self {
        Symbol {
            ns: Cow::from(ns),
            name: Cow::from(name),
        }
    }
}

fn main() {
    let mut m: HashMap<Symbol, u32> = HashMap::default();

    m.insert(Symbol::new("some-ns", "key"), 100);

    println!("{:?}", m);
    println!("v: {:?}", m.get(&Symbol::new("some-ns", "key")));
}