Merge two HashMaps in Rust

Question

So I\'m a bit stuck, trying to merge two HashMaps.

It\'s easy to do it inline:

fn inline() {
    let mut first_context = HashMap::new();
    first_co         


        

Answer 1

A more up to date answer from this tweet:

use std::collections::HashMap;

// Mutating one map
fn merge1(map1: &mut HashMap<(), ()>, map2: HashMap<(), ()>) {
    map1.extend(map2);
}

// Without mutation
fn merge2(map1: HashMap<(), ()>, map2: HashMap<(), ()>) -> HashMap<(), ()> {
    map1.into_iter().chain(map2).collect()
}

// If you only have a reference to the map to be merged in
fn merge_from_ref(map: &mut HashMap<(), ()>, map_ref: &HashMap<(), ()>) {
    map.extend(map_ref.into_iter().map(|(k, v)| (k.clone(), v.clone())));
}

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