Master Index
Every note by domain. Hub: Rust Brain Home.
Tooling & Getting Started · Tooling & Getting Started
Concepts: Anatomy of a Cargo Project · Cargo Basics · Cargo Build Run Check Test · The Guessing Game Tutorial · crates.io and Dependencies Intro · rustfmt and Clippy · rustup and Installation Patterns: Keep Application Logic Testable · Start Projects with cargo new · Use cargo check While Editing Anti-patterns: Using rustc Directly for Cargo-Sized Projects
Basic Concepts & Syntax · Basic Concepts & Syntax
Concepts: Arrays · Boolean Logic · Build-Time Code Execution · Comments · Constants · Control Flow · Functions · Generic Functions · If Expressions · Integer Overflow · Iterator Method Trio · Loop Expressions · Name Resolution · PartialEq · Private Fields with Public Constructors · Readable Generic APIs · Scalar Types · Shadowing · Statements vs Expressions · Static Items · The Debug Trait · The Display Trait · Tuples · Type Inference · UnsafeCell · Variables and Mutability · While and For Loops Patterns: Documentation Comments Anti-patterns: Relying on Integer Overflow
Ownership & Memory · Ownership & Memory
Concepts: Borrowing · Copy and Clone · Move Semantics · Mutable References · Ownership · References · The Drop Trait · The Slice Type · The Stack and the Heap Patterns: Borrowed Parameter APIs Anti-patterns: Returning References to Locals · Stale Slice Indices
Structs · Structs
Concepts: Associated Functions · Methods · Named Field Structs · Tuple Structs · Unit-Like Structs Patterns: Deriving Traits on Structs · Field Init Shorthand · Struct Update Syntax Anti-patterns: Expecting Per-Field Mutability in Structs · Partially Moved Structs with Update Syntax · Storing References in Structs Without Lifetimes
Enums & Pattern Matching · Enums & Pattern Matching
Concepts: Binding with @ · Destructuring · Enum Variants with Data · Enums · Exhaustiveness · Match Guards · Option · Patterns · Refutable and Irrefutable Patterns · The match Expression Patterns: Catch-All and Wildcard Patterns · if let · let else Anti-patterns: Overbroad Catch-All Match Arms · Pattern Variable Shadowing
Collections & Strings · Collections & Strings
Concepts: BTreeMap and BTreeSet · Capacity and Reallocation · HashMap · String and str · Vec · VecDeque Patterns: Borrowing Strings and Slices · Choosing Collection Types · Iterating Collections · The Entry API Anti-patterns: Holding Collection Element References Across Mutation · String Byte Indexing
Modules & Project Structure · Modules & Project Structure
Concepts: Crate Roots · Module Paths · Modules · Packages and Crates · Splitting Modules into Files · The use Keyword · Visibility and Privacy Patterns: Library and Binary Package Layout · Re-exporting with pub use · Workspace Project Structure Anti-patterns: Glob Imports in Public Code · Treating mod as include
Error Handling · Error Handling
Concepts: Custom Error Types · Error Sources and Chains · Option vs Result · Panic Unwinding and Abort · Recoverable vs Unrecoverable Errors · Result · The Error Trait · The Question Mark Operator · panic! Patterns: Adding Error Context · Application Errors with anyhow · Boxing Errors · Error Handling with thiserror · Propagating Errors · Returning Result from main Anti-patterns: Panicking in Libraries · Stringly-Typed Errors · Swallowing Errors · Unwrap and Expect Overuse
Generics, Traits & Lifetimes · Generics, Traits & Lifetimes
Concepts: Associated Types · Blanket Implementations · Coherence and the Orphan Rule · Default Implementations · Generic Associated Types · Generics · Lifetime Elision · Lifetimes · Marker Traits · Supertraits · The ‘static Lifetime · Trait Bounds · Traits · Where Clauses Patterns: Sealed Traits · Static Dispatch with Generics · Use a Newtype to Implement Foreign Traits Anti-patterns: Overconstraining Lifetimes · Overgeneric Public APIs · Unnecessary Bounds on Data Types
Closures & Iterators · Closures & Iterators
Concepts: Capturing the Environment · Closure Type Inference · Closures · Consuming Adapters · Fn, FnMut, FnOnce · Iterator Adapters · Iterators · Lazy Evaluation · The Iterator Trait · Zero-Cost Abstractions · move Closures Patterns: Prefer Iterator Pipelines to Manual Indexing · Return Iterators Instead of Collecting Anti-patterns: Manual Index Loops for Speed · Moving Out of FnMut Closures · Unconsumed Iterator Adapters
Smart Pointers & Interior Mutability · Smart Pointers & Interior Mutability
Concepts: Box · Cell · Cow · Deref and DerefMut · Interior Mutability · Rc · RefCell · Reference Cycles and Weak Patterns: Weak Back References Anti-patterns: Long-Lived RefCell Borrows
OOP & Trait Objects · OOP & Trait Objects
Concepts: Encapsulation in Rust · Object-Oriented Rust · Static vs Dynamic Dispatch · Trait Objects · dyn Compatibility (Object Safety) Patterns: Composition over Inheritance · The State Pattern · Type-State State Machines Anti-patterns: Non-dyn-Compatible Traits as Trait Objects · Overusing Trait Objects
Advanced Types & Features · Advanced Types & Features
Concepts: Associated Constants · Dynamically Sized Types · Fully Qualified Syntax · Function Pointers · Operator Overloading · Returning Closures · The Never Type · Type Aliases Patterns: Boxed Closure Returns · Newtype Pattern · Result Type Aliases Anti-patterns: Using Type Aliases as Newtypes
Macros · Macros
Concepts: Attribute Macros · Declarative Macros · Derive Macros · Function-like Macros · Macro Diagnostics · Macro Fragment Specifiers · Macro Hygiene · Macro Repetitions · Procedural Macros · macro_rules! · syn and quote Patterns: Exporting macro_rules Macros · Procedural Macro Crate Structure · Testing Macros with trybuild Anti-patterns: Ambiguous macro_rules Matchers · Unhygienic Procedural Macro Output
Concurrency · Concurrency
Concepts: Arc · Atomics · Barrier · Channels · Condvar · OnceLock and LazyLock · RwLock · Scoped Threads · Send and Sync · Shared State with Mutex · Threads · thread_local! Patterns: Arc Mutex Shared State · Deadlock Avoidance · Move Closures with Threads · Mutex Poisoning and Recovery Anti-patterns: Holding Locks Too Long · Ignoring Channel Disconnects · Lock Order Reversal · Unsafe Send and Sync Implementations
Async Rust · Async Rust
Concepts: Async Closures · Async Traits · Cancellation Safety · Futures · Pinning · Shared State in Async · Streams · Tasks and spawn · The Tokio Runtime · async and await · select! Patterns: Async Message Passing · Async Timeouts · LocalSet and Non-Send Futures · Scoping Non-Send Values Before Await · Structured Task Sets with JoinSet · spawn_blocking Anti-patterns: Blocking the Async Executor · Fire-and-Forget Tokio Tasks · Holding Locks Across Await · Non-Cancellation-Safe select! Branches
Unsafe Rust & FFI · Unsafe Rust & FFI
Concepts: Aliasing and Provenance · Dereferencing Raw Pointers · Extern statics · FFI with C · ManuallyDrop · MaybeUninit · Miri · Raw Pointers · Soundness vs Safety · Undefined Behavior · Unions · Unsafe Rust · unsafe extern Blocks · unsafe fn Patterns: FFI Wrapper Types · Pin projection · SAFETY Comments · Safe Abstractions over Unsafe Code Anti-patterns: The static mut Footgun and &raw · Transmute as a Shortcut
Testing & Documentation · Testing & Documentation
Concepts: Assertion Macros in Tests · Doctest Attributes · Documentation Tests · Ignored Tests · Integration Tests · Intra-doc Links · Test Functions · Test Harness and cargo test · Unit Tests · rustdoc Patterns: Result Returning Tests · Snapshot Testing · Test Organization · Test-Driven Development in Rust · Testable Documentation Examples Anti-patterns: Broad should_panic Tests · Shared State Between Parallel Tests · Untested Documentation Examples
Idioms & API Design · Idioms & API Design
Concepts: Conversion Traits Patterns: Accepting impl Trait vs Generics · AsRef for Flexible Arguments · Borrow for Equivalent Keys · Builder Pattern · Constructor Naming · Conversion Method Prefixes · From and Into · Making Invalid States Unrepresentable · Naming Conventions (Rust API Guidelines) · TryFrom and TryInto · Type-State Pattern Anti-patterns: Implementing Borrow for Partial Views · Panicking From Implementations
Anti-patterns & Footguns · Anti-patterns & Footguns
Anti-patterns: Blocking in Async · Deref Polymorphism Antipattern · Index Panics vs get · Integer Overflow Assumptions · Is Some Then Unwrap · Needless Clone · Premature Arc Mutex · Rc RefCell Overuse · Sentinel Values · Stringly-Typed Code · Unnecessary Collect
Cargo & Dependencies · Cargo & Dependencies
Concepts: Build Scripts (build.rs) · Cargo Configuration Hierarchy · Cargo Source Overrides · Cargo Workspaces · Cargo.lock · Cargo.toml Manifest · Dependencies and Version Requirements · Feature Flags · Feature Resolver · MSRV Policy · Profiles and Optimization Settings · Publishing to crates.io · Semantic Versioning Patterns: Minimizing Dependencies · Workspace Dependency Inheritance · cargo publish, yank and owners · cargo-audit and cargo-deny Anti-patterns: Non-Additive Feature Flags · Overbroad Version Requirements
Performance & Optimization · Performance & Optimization
Concepts: Iterator Performance · Profiling Rust Programs · SIMD and target_feature · The inline Attribute Patterns: Allocator Choices · Arena Allocation · Benchmarking with Criterion · Bounds-Check Elimination · Cache-Friendly Data Layout · Flamegraph and perf Workflow · LTO and codegen-units · Reducing Heap Allocations · SmallVec for Inline Storage Anti-patterns: Avoiding Premature Optimization · Speculative Micro-Optimization
Editions & Compiler · Editions & Compiler
Concepts: Codegen and Optimization Flags · Conditional Compilation (cfg) · Edition 2024 · Lints and Lint Levels · Rust Editions · Target Triples · The rustc Compiler Patterns: Enforcing Expected cfgs · Inspecting rustc Configuration · Migrating Editions Anti-patterns: Silencing Edition Migration Lints · Unchecked cfg Names
Embedded Rust · Embedded Rust
Concepts: Bare-Metal Programming · Embedded Rust Basics · Interrupts and Concurrency (Embedded) · Memory-Mapped IO · Peripheral Access Crates · no_std Patterns: Critical Sections in Embedded Rust · Heapless Collections in Embedded Rust Anti-patterns: Unsynchronized static mut in Interrupts
std: I/O & Formatting · std IO & Formatting
Concepts: Buffered IO with BufReader and BufWriter · Files in std::fs · Format Specifiers · Format Strings and format! · IO Errors and io::Result · OsStr and OsString · Path and PathBuf · Seek and Cursor · The Read and Write Traits Patterns: Implementing Display by Hand · Locking Stdin and Stdout · Reading Standard Input · Writing Standard Output
std: Collections Deep · std: Collections Deep
Concepts: BTreeMap Ordering and Ranges · BinaryHeap Priority Queues · HashMap Hashers and Key Invariants · HashMap Method Families · HashSet · LinkedList · Set Collections with HashSet and BTreeSet · VecDeque Ring Buffers Patterns: Choosing Standard Collections · Entry API for Accumulator Maps · try_reserve and Fallible Allocation Anti-patterns: HashMap Iteration Order Is Arbitrary · Mutating Collection Keys In Place
std: Core Trait Catalog · std: Core Trait Catalog
Concepts: Arithmetic Operator Traits Add and Mul · AsRef and AsMut Conversion Traits · Clone Semantics in std · Destructor Semantics with Drop · Display and Debug Formatting Traits · Equality Traits PartialEq and Eq · Fallible Conversion Traits (std) · Hash and Eq Contracts · Index and IndexMut Traits · Infallible Conversion Traits (std) · Iterator Conversion Traits IntoIterator and FromIterator · Ordering Traits PartialOrd and Ord · The Default Trait
std: Iterator Adapter Catalog · std: Iterator Adapter Catalog
Concepts: Iterator chain cycle and step_by · Iterator collect and FromIterator · Iterator flat_map and flatten · Iterator fold and reduce · Iterator map and filter · Iterator partition and unzip · Iterator predicate search adapters · Iterator rev and last · Iterator scan and peekable · Iterator sum product and count · Iterator take skip and while bounds · Iterator zip and enumerate
std: Option & Result Combinators · std: Option & Result Combinators
Concepts: Converting Between Option and Result · Option Combinators · Result Combinators · Transpose and Flatten Patterns: Chaining with and_then · Converting Option to Result with ok_or · Defaulting with unwrap_or Variants · Fallback Chains with or_else · Mapping Present Values with map · Predicate Checks with is_some_and and matches · Question Mark with Option Anti-patterns: Eager Work in Option and Result Defaults
std: Vec, String & Slices · std: Vec, String & Slices
Concepts: Bytes Chars and Unicode · Slicing and Range Indexing · String vs str Methods · Vec Capacity and Growth · Vec Methods Reference Patterns: Building Strings Efficiently · Filtering Vecs with dedup retain and drain · Sorting and Binary Search on Slices · Splitting Strings Without Collecting · Using chunks windows and split_at Anti-patterns: Assuming String Indexes Are Characters
Advanced Type System · Advanced Type System
Concepts: Const Generics and Const Parameters · Drop Check · Higher-Ranked Trait Bounds · PhantomData · Required Bounds on Generic Associated Types · Return-Position impl Trait in Traits · Trait Coherence and Covered Implementations · Type Layout and repr · Type layout · Variance · Zero-Sized Types Patterns: Lending Iterators with GATs · Phantom Type Parameters Anti-patterns: Uncovered Type Parameters in Foreign Impl
Ecosystem & Crate Playbooks · Ecosystem & Crate Playbooks
Concepts: Choosing the Right Rust Crate Patterns: Axum Web Service Playbook · Command-Line Parsing · Configuration Loading · Debugging · Itertools Iterator Helpers Playbook · Rayon Data Parallelism Playbook · Regex Text Matching Playbook · Reqwest HTTP Client Playbook · Serde Data Format Playbook · Tokio Runtime Playbook · Tracing and Structured Logging Playbook · clap Command Line Playbook
WebAssembly, no_std & Targets · WebAssembly, no_std & Targets
Concepts: Global Allocators · Panic Handlers · Panic Strategy Selection · Rust WebAssembly Targets · Target Features and CPU Baselines · Using alloc without std · alloc Collections in no_std · no_std Crate Design · wasm-bindgen Basics Patterns: Cargo Cross-Compilation Setup · Target-Specific cfg Boundaries Anti-patterns: Assuming wasm32 Means Browser