Rust: title case

playground.rs

fn title_case(s: &str) -> String {
    let mut c = s.chars();
    match c.next() {
        None => String::new(),
        Some(f) => f.to_uppercase().chain(c.flat_map(|t| t.to_lowercase())).collect(),

    }
}

fn main() {
    let s = "foo-bar_baz-QUAX";

    let us = s.split('-').map(|v| title_case(v)).collect::<Vec<_>>().join("-");
    
    println!("{}", us);

}

    for word in "The quick brown fox jumps over the lazy dog"
        .split_whitespace() 
        .map(|w| w.chars())
        .map(|mut c| 
            c.next().into_iter()
            .flat_map(|c| c.to_uppercase())
            .chain(c.flat_map(|c| c.to_lowercase())))
        .map(|c| c.collect::<String>()) 
    {
        print!("{:?} ", word); // "The" "Quick" "Brown" "Fox" "Jumps" "Over" "The" "Lazy" "Dog" 
    }