Symbols

Propagates an error to the caller if the result is Err

When calling a function that returns Result or Option

let data = read_file(path)?;
// returns Err up if it fails

Navigates into a type, module, or enum to access items inside

Calling associated functions or accessing enum variants

let s = String::from("hi");
let v = Vec::new();

Separates a match pattern from the code that runs for that case

Inside a match block, one per case

match coin { Heads => 1,
Tails => 0 }

Wraps a closure's parameters; defines an inline anonymous function

Passing logic to iterators like map or filter

let double = |x| x * 2;
double(5) // returns 10

An exclusive range: start up to but not including end

Looping over a count or slicing a collection

for i in 0..5 {
// i = 0, 1, 2, 3, 4

An inclusive range: start through and including end

When you need to include the last value in a range

for i in 0..=5 {
// i = 0, 1, 2, 3, 4, 5

An attribute that tells the compiler how to handle the next item

Deriving traits or marking types for special behavior

#[derive(Debug, Clone)]
struct Point { x: i32 }

Makes an item visible and usable outside its current module

When a function, struct, or field needs to be public

pub fn transfer() { }
pub struct Account { }