use decoder::{Map, Result, Value};

struct Person {
    name: String,
    projects: Vec<Project>,
}

struct Project {
    name: String,
    url: String,
}

impl Person {
    fn decode(value: Value) -> Result<Self> {
        use decoder::decode::{map, sequence, string};

        let mut person = map(value)?;

        Ok(Self {
            name: person.required("name", string)?,
            projects: person.required("projects", sequence(Project::decode))?,
        })
    }

    fn encode(&self) -> Value {
        use decoder::encode::{map, sequence, string};

        map([
            ("name", string(&self.name)),
            ("projects", sequence(Project::encode, &self.projects)),
        ])
        .into()
    }
}

impl Project {
    fn decode(value: Value) -> Result<Self> {
        use decoder::decode::{map, string};

        let mut project = map(value)?;

        Ok(Project {
            name: project.required("name", string)?,
            url: project.required("url", string)?
        })
    }

    fn encode(&self) -> Value {
        use decoder::encode::{map, string};

        map([
            ("name", string(&self.name)),
            ("url", string(&self.url)),
        ])
        .into()
    }
}

let person =
    decoder::run(serde_json::from_str, Person::decode, "{ ... }").expect("Decode person");

let _ = serde_json::to_string(&person.encode());