Karatasi ya Muhtasari ya Rust

Bila Malipo

Rejeo la Rust linalotafutika na kuchapishika: ownership na borrowing, traits, pattern matching, Option na Result, iterators na Cargo. Bure.

Basics

let x = 5;

Immutable binding (default)

let mut count = 0; count += 1;

Mutable binding

let x = "5"; let x: i32 = x.parse()?;

Shadowing (new type allowed)

i32, u64, f64, bool, char, usize

Core scalar types

let t = (1, "a"); t.0

Tuple + field access

let a = [0u8; 16];

Fixed array of 16 zeros

const MAX_USERS: u32 = 100;

Compile-time constant

let n = big as u8;

Explicit numeric cast

let s: String; let sl: &str;

Owned string vs string slice

println!("{name} has {count}");

Inline variable interpolation

Ownership, borrowing & lifetimes

let b = a; // a is moved

Assignment moves non-Copy types

let b = a.clone();

Deep copy keeps both usable

fn read(s: &String) / read(&s)

Shared borrow (many allowed)

fn edit(s: &mut String) / edit(&mut s)

Exclusive borrow (only one)

// no &mut while & borrows live

The core borrow rule

fn greet(name: &str)

Prefer &str params over &String

i32, bool, char, &T are Copy

Copy types never move

fn first<'a>(a: &'a str, b: &str) -> &'a str

Tie output to an input lifetime

struct View<'a> { text: &'a str }

Struct holding a reference

let s: &'static str = "literal";

Lives for the whole program

Structs, enums & impl

struct User { name: String, age: u32 }

Struct definition

let u = User { name, age: 30 };

Literal + field-init shorthand

let u2 = User { age: 31, ..u };

Struct update syntax

struct Meters(f64);

Tuple struct (newtype idiom)

impl User { fn new(name: String) -> Self { ... } }

Associated constructor

fn label(&self) -> String

Method borrowing self

fn rename(&mut self, n: String)

Method mutating self

enum Shape { Circle(f64), Rect { w: f64, h: f64 } }

Enum with data per variant

#[derive(Debug, Clone, PartialEq)]

Auto-implement common traits

let cfg = Config::default();

Default trait construction

Pattern matching

match n { 0 => "zero", _ => "other" }

Exhaustive match expression

match shape { Shape::Circle(r) => ... }

Destructure enum variants

match n { 1..=5 => "low", _ => "high" }

Range patterns

match p { Point { x, y: 0 } => ... }

Destructure struct fields

Some(n) if n > 10 => "big"

Match guard

id @ 1..=9 => use(id)

Bind while matching (@)

if let Some(v) = opt { use(v); }

Match a single pattern

let Some(v) = opt else { return; };

let-else early exit

while let Some(x) = stack.pop() { ... }

Loop while a pattern holds

matches!(status, Status::Active)

Boolean pattern test macro

Option & Result

let opt: Option<i32> = Some(5);

Maybe-a-value type

let res: Result<T, E> = Ok(v);

Success-or-error type

let v = load()?;

? propagates None / Err up

opt.unwrap_or(0)

Value or a default

opt.unwrap_or_else(|| compute())

Lazy default

opt.unwrap_or_default()

Value or Default::default()

opt.map(|v| v * 2)

Transform if present

opt.and_then(|v| v.checked_mul(2))

Chain fallible steps (flatMap)

opt.ok_or(MyError::Missing)?

Option → Result

res.map_err(|e| AppError::Io(e))

Convert the error type

opt.is_some(); res.is_err();

Cheap state checks

let v = opt.take();

Move out, leave None behind

Traits & generics

trait Greet { fn hello(&self) -> String; }

Trait: shared behavior

trait Greet { fn wave(&self) { ... } }

Default method body

impl Greet for User { ... }

Implement for a type

fn welcome<T: Greet>(x: &T)

Generic with a trait bound

fn f<T>(x: T) where T: Greet + Clone

where clause for many bounds

fn welcome(x: &impl Greet)

impl Trait argument sugar

fn make() -> impl Iterator<Item = u32>

Opaque return type

let objs: Vec<Box<dyn Greet>> = ...;

Trait objects (dynamic dispatch)

impl From<u32> for Meters { ... }

From gives you Into for free

let m: Meters = 5u32.into();

Convert via Into

impl fmt::Display for User { ... }

Custom {} formatting

Collections

let mut v = vec![1, 2, 3];

Vec literal macro

v.push(4); v.pop();

Append / remove last

v.get(0) // Option<&T>

Safe indexing (v[9] panics)

for x in &v { ... }

Iterate by reference

v.sort(); v.sort_by_key(|u| u.age);

In-place sorting

v.retain(|x| *x > 0);

Keep matching elements

let mut m = HashMap::new(); m.insert(k, v);

Hash map basics

*counts.entry(word).or_insert(0) += 1;

Entry API counter idiom

m.contains_key(&k); m.get(&k);

Lookups return Option

s.push_str("more"); format!("{a}{b}")

Grow / build strings

s.chars().rev().collect::<String>()

Char-wise string processing

names.join(", ")

Join a Vec<String>

Iterators & closures

v.iter().map(|x| x * 2).collect::<Vec<_>>()

Transform and materialize

.filter(|x| **x > 0)

Keep matching elements

.filter_map(|s| s.parse().ok())

Filter + map in one pass

.sum::<i32>(); .count(); .max()

Common consumers

.fold(0, |acc, x| acc + x)

General reduction

.enumerate()

Pairs of (index, item)

.zip(other.iter())

Walk two iterators together

.take(5); .skip(2); .rev()

Slice and reverse lazily

.flat_map(|l| l.split(' '))

Map then flatten

.any(|x| x < 0); .all(|x| x > 0)

Short-circuit predicates

.find(|u| u.id == id); .position(...)

First match / its index

iter() &T; iter_mut() &mut T; into_iter() T

The three iteration modes

let add = move |x| x + base;

move closure takes ownership

.collect::<HashMap<_, _>>()

Collect pairs into a map

Error handling

fn run() -> Result<(), Box<dyn Error>>

Quick catch-all error type

fn main() -> anyhow::Result<()>

anyhow for applications

file.read().context("reading config")?;

anyhow: attach context

anyhow::bail!("invalid input: {x}");

Early return with an error

#[derive(thiserror::Error, Debug)]

thiserror for libraries

#[error("user {0} not found")] NotFound(u64),

Display message per variant

#[error(transparent)] Io(#[from] std::io::Error),

Auto-From wrapped errors

enum AppError { Db(String), Timeout }

Custom error enum

let n = do_it()?; // Err auto-converts

? uses From between error types

opt.expect("config must be loaded")

unwrap/expect: tests only

eprintln!("error: {e:#}");

Print the full error chain

Smart pointers & interior mutability

let b = Box::new(BigStruct::new());

Heap allocation, sole owner

enum List { Node(i32, Box<List>), Nil }

Box enables recursive types

let a = Rc::new(data); let b = Rc::clone(&a);

Shared owner, single thread

let a = Arc::new(data);

Shared owner across threads

let c = RefCell::new(0); *c.borrow_mut() += 1;

Runtime-checked mutation

Rc<RefCell<T>>

Shared + mutable (one thread)

let m = Mutex::new(0); *m.lock().unwrap() += 1;

Thread-safe mutation

Arc<Mutex<T>>

Shared + mutable across threads

let l = RwLock::new(map); l.read(); l.write();

Many readers or one writer

Cell::new(5).set(6);

Copy-type interior mutability

let w = Rc::downgrade(&a); w.upgrade()

Weak breaks reference cycles

Concurrency & async

let h = thread::spawn(|| work()); h.join()

Spawn and join a thread

thread::spawn(move || use(data))

move data into the thread

thread::scope(|s| { s.spawn(|| ...); })

Borrow locals in threads

let (tx, rx) = mpsc::channel();

Multi-producer channel

tx.send(job)?; let job = rx.recv()?;

Send / blocking receive

let n = Arc::new(Mutex::new(0));

Shared counter pattern

#[tokio::main] async fn main() { ... }

Async runtime entry point

async fn fetch() -> Result<Data>

Async function

let data = fetch().await?;

Await a future

let h = tokio::spawn(fetch()); h.await??;

Spawn an async task

let (a, b) = tokio::join!(f1(), f2());

Run futures concurrently

tokio::time::sleep(Duration::from_secs(1)).await;

Non-blocking sleep

tokio::select! { r = f1() => ..., _ = f2() => ... }

First future to finish wins

Cargo CLI

cargo new my-app

Create a binary project

cargo add serde --features derive

Add a dependency

cargo run

Build and run (debug)

cargo build --release

Optimized build

cargo check

Type-check fast, no binary

cargo test

Run tests (+ doc tests)

cargo clippy -- -D warnings

Lints, warnings as errors

cargo fmt

Format the whole project

cargo doc --open

Build and browse the docs

cargo update

Refresh Cargo.lock versions

cargo install ripgrep

Install a binary crate

cargo tree

Show the dependency graph

Hakuna kipengele kinacholingana na “:q”.

Kuhusu Karatasi ya Muhtasari ya Rust

Karatasi hii ya muhtasari ya Rust inapanga lugha kwa dhana kwenye ukurasa mmoja unaotafutika: misingi, ownership, borrowing na lifetimes, structs, enums na impl blocks, pattern matching, Option na Result, traits na generics, collections, iterators na closures, ushughulikiaji wa makosa, smart pointers na interior mutability, concurrency na async, na mstari wa amri wa Cargo.

Ownership ndiyo sehemu ya Rust ambayo watu hurudi kutafuta, kwa hivyo ina sehemu yake kando ya lifetimes, kanuni za borrowing, Box, Rc, Arc na RefCell: pamoja na sintaksia ya kila siku kama match arms, opereta ya ?, iterator adapters na deriving traits.

Kama kila karatasi ya muhtasari katika kundi hili ni bure na inafanya kazi upande wa mteja: chuja safu moja kwa moja kwa kisanduku cha utafutaji, ruka kati ya sehemu kwa jedwali la yaliyomo linalobaki juu, nakili kijisehemu chochote kwa mbofyo mmoja na chapisha ukurasa kuwa rejeo la mezani.

Jinsi ya kutumia Karatasi ya Muhtasari ya Rust

Fungua karatasi na upitie sehemu, kuanzia Basics na Ownership & borrowing hadi Cargo CLI.
Tafuta neno kuu kama lifetime, match au Arc ili kuchuja karatasi moja kwa moja.
Ruka hadi Option & Result au Error handling unapohitaji njia ya kimtindo ya kushindwa.
Bofya kijisehemu au ikoni yake ya kunakili ili kunakili msimbo wa Rust kwenye ubao wako wa kunakili.
Tumia Chapisha kupata nakala ya karatasi ya rejeo kamili ya Rust.

Maswali yanayoulizwa mara kwa mara

Sehemu kumi na mbili: misingi, ownership, borrowing na lifetimes, structs, enums na impl, pattern matching, Option na Result, traits na generics, collections, iterators na closures, ushughulikiaji wa makosa, smart pointers na interior mutability, concurrency na async, na Cargo CLI.

Ndiyo. Sehemu maalum inaonyesha moves, borrows, mutable borrows, kanuni za borrow-checker na maelezo ya lifetime pamoja na maelezo mafupi kwenye kila safu.

Ndiyo: combinators za Option na Result, opereta ya ?, aina maalum za makosa, ubadilishaji wa From na mifumo ya kawaida ya crate kila kimoja kinaonekana kama kijisehemu tayari kunakiliwa.

Ndiyo. Bofya msimbo kwenye safu yoyote au ikoni yake ya kunakili na utanakiliwa papo hapo.

Ndiyo, ni bure kabisa na hufanya kazi kwenye kivinjari chako bila kuingia.

Utafutaji maarufu

rust cheat sheet rejeo la sintaksia ya rust rust ownership na borrowing maelezo ya rust lifetimes option na result katika rust rust traits na generics amri za cargo

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