Rust

A .rs file imports like a header: crossbind binds its public structs and functions, so Rust sits beside C++ in one project.

words.rs defines a struct, Tally, with its methods in an impl, and a function, parse_score. The struct arrives as a class whose constructor is new, and snake_case names arrive in camelCase: parseScore.

A String is a string and a Vec an array, with no helper, and None is null. A function that returns a Result returns what Ok holds and throws an Err as an Error with the error's text.

A crate from crates.io imports the same way, as cargo:<crate>; the next step uses one, and the Rust guide maps every type.

Try it

Give Tally a pub fn shortest(&self) -> Option<String> and print tally.shortest().

// A pub struct with its impl arrives as a class, with `new` as
// its constructor, and a pub fn as a function. Names written in
// snake_case are camelCase in JavaScript.
pub struct Tally {
    words: Vec<String>,
}
 
impl Tally {
    pub fn new() -> Self {
        Tally { words: Vec::new() }
    }
 
    pub fn add(&mut self, text: &str) {
        for word in text.split_whitespace() {
            self.words.push(word.to_string());
        }
    }
 
    pub fn longest(&self) -> Option<String> {
        self.words.iter().max_by_key(|word| word.len()).cloned()
    }
 
    pub fn words(&self) -> Vec<String> {
        self.words.clone()
    }
}
 
pub fn parse_score(text: &str) -> Result<i32, String> {
    match text.parse::<i32>() {
        Ok(score) if (0..=100).contains(&score) => Ok(score),
        Ok(score) => Err(format!("{score} is out of range")),
        Err(_) => Err(format!("{text} is not a number")),
    }
}
 
 
// A pub struct with its impl arrives as a class, with `new` as
// its constructor, and a pub fn as a function. Names written in
// snake_case are camelCase in JavaScript.
pub struct Tally {
    words: Vec<String>,
}

impl Tally {
    pub fn new() -> Self {
        Tally { words: Vec::new() }
    }

    pub fn add(&mut self, text: &str) {
        for word in text.split_whitespace() {
            self.words.push(word.to_string());
        }
    }

    pub fn longest(&self) -> Option<String> {
        self.words.iter().max_by_key(|word| word.len()).cloned()
    }

    pub fn words(&self) -> Vec<String> {
        self.words.clone()
    }
}

pub fn parse_score(text: &str) -> Result<i32, String> {
    match text.parse::<i32>() {
        Ok(score) if (0..=100).contains(&score) => Ok(score),
        Ok(score) => Err(format!("{score} is out of range")),
        Err(_) => Err(format!("{text} is not a number")),
    }
}

Open in playgroundRuns without a compile until the C++, Rust, packages or imports change.

Console

Press Run, or Ctrl+Enter, to run main.js.