pig latin

background

The final section of the eighth chapter of the rust book ends with some suggested exercises. The second of which is to write a program that:

Convert strings to Pig Latin. The first consonant of each word is moved to the end of the word and ay is added, so first becomes irst-fay. Words that start with a vowel have hay added to the end instead (apple becomes apple-hay). Keep in mind the details about UTF-8 encoding!

solution

At the time, I thought the simplest approach would be to find Rust’s set-like structure to store and test for vowels. It seemed like a HashSet was that structure:

use std::collections::HashSet;


fn main() {
    let w1 = String::from("apple");
    let w2 = String::from("first");
    println!("{}", to_pig_latin(&w1));
    println!("{}", to_pig_latin(&w2));
}

fn to_pig_latin(word: &String) -> String {
    let vowels = HashSet::from(['a', 'e', 'i', 'o', 'u']);
    let first = word.chars().next().unwrap();
    if vowels.contains(&first) {
        return format!("{word}hay")
    } else {
        let rest = &word[1..];
        return format!("{rest}{first}ay")
    }
}

applehay
irstfay

Looking back, we could have made vowels a global constant.

There’s also a bug when word is an empty string; we unwrap irresponsibly without handling when there is no next.

Something like this could have been better in retrospect:

let first = match word.chars().next() {
    Some(character) => character,
    None => return String::new()
};