std::process::Command runs external programs and captures their output. I use it for CLI tools that wrap other commands, build scripts, or integration tests. Methods like .arg(), .env(), and .current_dir() configure the process. .output() runs and wai

AsRef<T> is a trait for cheap reference-to-reference conversion. It's commonly used in function parameters to accept multiple types. For example, a function taking impl AsRef<Path> can accept &Path, PathBuf, &str, or String. This i

Implementing Deref lets your type automatically coerce to its target type. For example, Box<T> derefs to T, and String derefs to str. This enables method calls and conversions without explicit unwrapping. I implement Deref for wrapper types and

Associated types let a trait declare a type that implementors must define. This is cleaner than adding a generic parameter to the trait. For example, Iterator has an associated type Item rather than being Iterator<Item>. I use associated types w

impl Trait in return position lets you return a type that implements a trait without naming it. This is useful for closures, iterators, or futures where the concrete type is complex or unnameable. The caller only knows it implements the trait. I use i

const defines compile-time constants, and const fn are functions that can run at compile time. I use const for magic numbers, lookup tables, and configuration that never changes. const fn is powerful for building complex constants (like hash maps or a

Most types in Rust are Sized (known size at compile time), which is an auto trait. Some types like str or [T] are !Sized (dynamically-sized types, DSTs). To work with DSTs, use &T or Box<T>. In generic code, T: Sized is the default bound. To

color-eyre enhances eyre (an anyhow alternative) with colored, human-readable error messages and backtraces. It automatically captures panic backtraces and suggestion hints. I use it in CLI tools where error UX matters. The setup is minimal: color_eyr

Nom is a parser combinator library for building parsers from small, composable functions. It's byte-oriented and zero-copy, making it ideal for binary protocols, config files, or log parsing. I define parsers for tokens (like tag("GET") or digit1), th

parking_lot provides drop-in replacements for Mutex, RwLock, and Condvar that are faster and smaller than std::sync. They use more efficient parking/unparking and don't poison on panic. I use parking_lot::Mutex in hot paths where lock contention matte

Crossbeam provides lock-free data structures and utilities for concurrent programming. The crossbeam-channel crate offers multi-producer multi-consumer channels with better performance than std::sync::mpsc. crossbeam-utils has scoped threads (borrow d

The log crate provides logging macros (error!, warn!, info!, debug!, trace!) that are backend-agnostic. Libraries use log, and applications choose the backend (env_logger, simple_logger, or tracing). This decouples logging from the implementation. I u