Building a serde_yaml Mapping

serde_yaml_mapping.rs

// adapted from serde_json example: https://stackoverflow.com/a/39147207

extern crate serde_yaml;
use serde_yaml::{Value, Mapping, Number};

fn main() {
    let mut inner_map = Mapping::new();
    inner_map.insert(Value::String("x".to_string()), Value::Number(Number::from(10u64)));
    inner_map.insert(Value::String("y".to_string()), Value::Number(Number::from(20u64)));

    let mut map = Mapping::new();
    map.insert(Value::String("key1".to_string()), Value::String("test".to_string()));
    map.insert(
        Value::String("key2".to_string()),
        Value::Sequence(vec![
            Value::String("a".to_string()),
            Value::String("b".to_string()),
        ]),
    );
    map.insert(Value::String("key3".to_string()), Value::Mapping(inner_map));

    println!("{}", serde_yaml::to_string(&map).unwrap());
    // ---
    // key1: test
    // key2:
    //   - a
    //   - b
    // key3:
    //   x: 10
    //   y: 20
}

The above code can be directly run in the Rust Playground: https://play.rust-lang.org