🦀 Rust Handbook

Overview

Rust is a systems programming language focused on safety, speed, and concurrency — without a garbage collector. It prevents memory bugs at compile time through its ownership model.

Edition Rust 2021  Paradigm Systems, Functional  Typing Static, Strong

Core Concepts

Ownership & Borrowing

• Each value has a single owner
• Value dropped when owner goes out of scope
• Borrowing: &T (immutable) / &mut T (mutable)
• Only one mutable borrow OR many immutable borrows at a time
• Lifetimes ensure references are valid

Variables & Types

• Immutable by default: let x = 5;
• Mutable: let mut x = 5;
• Scalar: i32, u64, f64, bool, char
• Compound: tuples, arrays
• Heap: String, Vec<T>, Box<T>

Control Flow

• if / else if / else (expressions, not statements)
• loop, while, for x in iter
• match — exhaustive pattern matching

Enums & Pattern Matching

• Option<T> — Some(T) | None (no null)
• Result<T, E> — Ok(T) | Err(E) for error handling
• ? operator for early error return
• Rich match with guards and destructuring

Key Crates & Tools

Category	Crate / Tool
Web	Actix-web, Axum, Rocket
Async	Tokio, async-std
Serialization	serde, serde_json
CLI	clap, structopt
Testing	Built-in #[test], proptest
Build	Cargo (package manager + build tool)

Common Interview Topics

• Ownership vs borrowing vs lifetimes
• Stack vs heap allocation in Rust
• Trait objects (dyn Trait) vs generics
• Smart pointers: Box, Rc, Arc, RefCell
• Fearless concurrency with Send + Sync traits
• Zero-cost abstractions