Rust Patterns Basics

struct UserId(u64);
struct OrderId(u64);
// cannot pass OrderId where UserId expected

let client = Client::builder()
    .timeout(Duration::from_secs(5))
    .build()?;

struct LockGuard<'a>(&'a mut State);
impl Drop for LockGuard<'_> {
    fn drop(&mut self) { /* release */ }
}

impl From<u64> for UserId {
    fn from(id: u64) -> Self { UserId(id) }
}
let id: UserId = 42.into();

trait StrExt {
    fn trimmed(&self) -> &str;
}
impl StrExt for str {
    fn trimmed(&self) -> &str { self.trim() }
}

struct Connection<State> { /* ... */ }
struct Open;
struct Closed;

use std::cell::RefCell;
let cache = RefCell::new(HashMap::new());

fn load() -> Result<Data, Error> {
    let raw = read_file().context("read config")?;
    parse(raw).context("parse config")
}

let active: Vec<_> = users.iter().filter(|u| u.active).map(|u| u.id).collect();