Rust's async/await syntax lets you write asynchronous code that looks synchronous. An async fn returns a Future, which is a lazy computation. Calling .await yields control until the future is ready, allowing other tasks to run. Tokio is the most popul

Rust's mpsc (multiple producer, single consumer) channels are the safest way to communicate between threads. You send owned values through the channel, transferring ownership to the receiver. This prevents data races because only one thread owns the d

When you need shared mutable state across threads, Arc<Mutex<T>> is the idiomatic pattern. Arc is an atomic reference counter that allows multiple ownership, and Mutex provides interior mutability with runtime locking. You clone the Arc fo

When a struct holds a reference, you must annotate its lifetime so the compiler knows the reference won't outlive the data. The syntax <'a> declares a lifetime parameter, and &'a str ties the reference to that lifetime. This ensures that as

Instead of transferring ownership, Rust lets you borrow values with references (&T for immutable, &mut T for mutable). Borrows allow functions to read or modify data without taking ownership, so the caller retains access afterward. The borrow

Rust's ownership system guarantees memory safety without garbage collection. Each value has exactly one owner, and when ownership is transferred (moved), the previous owner can't use it anymore. This prevents double-frees and use-after-free bugs at co

When prototyping or writing applications (not libraries), anyhow is my go-to. It provides Result<T> as an alias for Result<T, anyhow::Error>, which can hold any error type. The .context() method attaches additional context to errors as the

For production code, I define custom error enums using thiserror. It auto-derives Display and Error trait implementations, making errors self-documenting and composable. Each variant can wrap underlying errors (#[from]) for automatic conversion with ?

Rust's Result<T, E> forces you to handle errors explicitly, but the ? operator makes it ergonomic. When a function returns Result, using ? automatically returns early with the error if it's Err, or unwraps the value if it's Ok. This replaces ver

Flash messages provide one-time notifications across requests, perfect for confirming actions or showing errors. I use flash[:notice] for success messages and flash[:alert] for errors. Flash persists in session storage for one request, then auto-delet

The Intersection Observer API efficiently detects when elements enter/exit the viewport, enabling lazy loading, infinite scroll, and analytics without expensive scroll listeners. I create observers with thresholds defining when callbacks trigger—0.0 m

Service objects encapsulate complex business logic that doesn't belong in models or controllers. Each service performs one operation, like creating a post with side effects, processing a payment, or importing data. I create services in app/services wi