RandyMcMillan

use anyhow::Result;

// The same function as before that might fail.
fn get_user_id(username: &str) -> Result<u32> {
    if username.is_empty() {
        anyhow::bail!("Username cannot be empty");
    }
    Ok(42)
}

RandyMcMillan

use anyhow::Result;

// A function that returns a Result.
// We use 'anyhow::Result' as a shorthand for 'Result<T, anyhow::Error>'.
fn get_user_id(username: &str) -> Result<u32> {
    // This is a simple, illustrative error case.
    // We can use anyhow::bail! to create an immediate error.
    if username.is_empty() {
        // 'anyhow::bail!' is a macro that returns an error.
        anyhow::bail!("Username cannot be empty");

RandyMcMillan

// https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=f6b6cbb5fedbb3a745ee98fde30c8d06
// A basic struct that holds an array of 16-bit unsigned integers.
struct Numbers([u16; 10]);

// Implement the IntoIterator trait for our Numbers struct.
impl<'a> IntoIterator for &'a Numbers {
    // We want to iterate over references to u16 values.
    type Item = &'a u16;
    // The type of the iterator we're returning.
    type IntoIter = std::slice::Iter<'a, u16>;

RandyMcMillan

use std::rc::Rc;
fn process_shared(data: Rc<String>, storage: &mut Vec<Rc<String>>) {
    storage.push(data.clone()); // Clones Rc, not String
}
fn main() {
    let shared = Rc::new("shared".to_string());
    let mut storage = Vec::new();
    while Rc::strong_count(&shared) < 10 {
        process_shared(shared.clone(), &mut storage);
        println!("Rc count: {}", Rc::strong_count(&shared));

RandyMcMillan

#[allow(dead_code)]
#[derive(Debug)]
enum ConfigError {
    MissingKey(String),
    ParseError(std::num::ParseIntError),
}
impl From<std::num::ParseIntError> for ConfigError {
    fn from(err: std::num::ParseIntError) -> Self {
        ConfigError::ParseError(err)
    }

RandyMcMillan

use tokio::io::{AsyncReadExt, AsyncWriteExt};
use tokio::net::TcpListener;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let listener = TcpListener::bind("127.0.0.1:8080").await?;
    println!("Echo server listening on 127.0.0.1:8080");

    loop {
        let (mut socket, addr) = listener.accept().await?;

RandyMcMillan

use std::collections::BTreeMap;
fn main() {
    // Let's create a nested B-tree structure:
    // A BTreeMap where keys are strings (e.g., "country")
    // and values are another BTreeMap (e.g., "city" -> population).
    let mut world_populations: BTreeMap<String, BTreeMap<String, u64>> = BTreeMap::new();

    // Add some data for "USA"
    let mut usa_cities = BTreeMap::new();
    usa_cities.insert("New York".to_string(), 8_468_000);

RandyMcMillan

fn is_palindrome(n: u64) -> bool {
    if n < 10 {
        return true; // Single-digit numbers are palindromes
    }
    let s = n.to_string();
    s == s.chars().rev().collect::<String>()
}

fn generate_palindromes_up_to(limit: u64) -> Vec<u64> {
    let mut palindromes = Vec::new();

RandyMcMillan

use tokio::io::{AsyncReadExt, AsyncWriteExt};
use tokio::net::TcpListener;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let listener = TcpListener::bind("127.0.0.1:8080").await?;
    println!("Echo server listening on 127.0.0.1:8080");

    loop {
        let (mut socket, addr) = listener.accept().await?;

RandyMcMillan

Dealing with Rust to build PactSwiftMockServer

Example of an automated script that does most of this: https://github.com/surpher/PactSwiftMockServer/blob/fb8148866bb05f49a0b1dcaae66c67bad1e7eca7/Support/build_rust_dependencies

Install Rust

curl https://sh.rustup.rs -sSf | sh