Rust Patterns

Prescriptive patterns for writing idiomatic Rust, extracted from the standard library source at rust-lang/rust.

Source

All patterns are extracted from the library/ directory (the standard library implementation) at commit f53b654 (325,000 commits, 8,021 contributors).

Pattern Files

File	Patterns	Lines	Key Topics
error-handling.md	10	702	Result, ?, Error trait, From, panic!
traits.md	10	699	Small traits, derive, From/Into, Iterator, Deref
ownership.md	10	677	Borrowing, Clone/Copy, Cow, Arc, Drop, lifetimes
documentation.md	10	723	Doc comments, # Safety, # Examples, doc tests
concurrency.md	10	723	Send/Sync, Mutex, atomics, channels, scoped threads
testing.md	10	664	cfg(test), assert_eq!, should_panic, property tests
unsafe-patterns.md	10	624	// SAFETY:, unsafe fn, MaybeUninit, FFI
api-design.md	10	596	Naming, #[non_exhaustive], newtype, typestate
module-organization.md	10	514	File structure, pub use, prelude, workspaces
macros.md	10	519	macro_rules!, derive, attribute macros, hygiene

Total: 100 patterns across 10 files + 20 smells across 2 files = 7,439 lines.

Discovery Data (from library/)

Category	Metric	Count
Error Handling	? operator usages	4,702
Error Handling	Result<> types	4,059
Error Handling	From<> impls	508
Traits	Public traits	241
Traits	Trait implementations	4,387
Traits	Iterator impls	895
Ownership	&mut references	7,909
Ownership	Rc/Arc usages	798
Ownership	Cow<> usages	197
Documentation	Doc comments (///)	133,741
Documentation	# Examples sections	3,912
Documentation	# Safety sections	2,864
Concurrency	Atomic types	783
Concurrency	Send/Sync markers	274
Testing	#[test] functions	4,136
Testing	Assert macros	16,728
Unsafe	Unsafe blocks	31,244
Unsafe	// SAFETY: comments	2,463
API Design	pub fn	18,430
API Design	pub(crate)	919
Macros	macro_rules!	607
Macros	#[derive(...)]	1,116

Smell Files

File	Entries	Lines	Key Topics
smells/anti-patterns.md	10	490	unwrap in libs, String errors, unsafe without SAFETY, clone escape
smells/common-mistakes.md	10	508	Arc everywhere, collect then iterate, index loops, OOP thinking

Each Pattern Includes

• Source hyperlink — permalink to the exact source location
• Before/After code — concrete transformation showing improvement
• When to Use — trigger conditions (when this pattern applies)
• When NOT to Use — over-application warning with code example
• Decision tree — at the end of each file for quick reference

How to Use This Repo

1. Learning Rust: Read patterns in order of importance: error-handling → ownership → traits → concurrency
2. Code review: Reference specific patterns when reviewing Rust PRs
3. Teaching: Use before/after pairs as exercises
4. Writing new code: Check the decision tree before choosing an approach

Related Repos

• rodin/go-patterns — Go patterns from stdlib
• rodin/elixir-patterns — Elixir patterns from stdlib
• rodin/codebase-analysis — The skill that produces these repos

License

This repository contains analysis and patterns derived from rust-lang/rust (MIT/Apache-2.0 dual licensed).