Code shared from the Rust Playground

playground.rs

#[allow(dead_code)]
#[allow(non_snake_case)]
#[allow(non_camel_case_types)]
mod NumberFormat {
    #[derive(Debug)]
    pub enum Style {
        DECIMAL,
        CURRENCY,
        PERCENT,
    }

    impl Default for Style {
        fn default() -> Style {
            Style::DECIMAL
        }
    }

    #[derive(Debug)]
    pub enum Opt {
        style(Style),
        currency(String),
        maximumFractionDigits(i32),
    }
    
    pub fn build(locale: &str, options: &[Opt]) {
        print!("{:?} {:?}", locale, options);
    }
}

fn main() {
    NumberFormat::build("pt-BR", &[
        NumberFormat::Opt::style(NumberFormat::Style::CURRENCY),
        NumberFormat::Opt::currency(String::from("EUR")),
    ]);
}