as: primitive casting, or disambiguating the specific trait containing an item. See Casting Between Types (as) , Universal Function Call Syntax (Angle-bracket Form) , Associated Types .break: break out of loop. See Loops (Ending Iteration Early) .const: constant items and constant raw pointers. See const and staticRaw Pointers .continue: continue to next loop iteration. See Loops (Ending Iteration Early) .crate: external crate linkage. See Crates and Modules (Importing External Crates) .else: fallback for if and if let constructs. See ifif letenum: defining enumeration. See Enums .extern: external crate, function, and variable linkage. See Crates and Modules (Importing External Crates) , Foreign Function Interface .false: boolean false literal. See Primitive Types (Booleans) .fn: function definition and function pointer types. See Functions .for: iterator loop, part of trait impl syntax, and higher-ranked lifetime syntax. See Loops (for) , Method Syntax .if: conditional branching. See ifif letimpl: inherent and trait implementation blocks. See Method Syntax .in: part of for loop syntax. See Loops (for) .let: variable binding. See Variable Bindings .loop: unconditional, infinite loop. See Loops (loop) .match: pattern matching. See Match .mod: module declaration. See Crates and Modules (Defining Modules) .move: part of closure syntax. See Closures (move closures) .mut: denotes mutability in pointer types and pattern bindings. See Mutability .pub: denotes public visibility in struct fields, impl blocks, and modules. See Crates and Modules (Exporting a Public Interface) .ref: by-reference binding. See Patterns (ref and ref mut) .return: return from function. See Functions (Early Returns) .Self: implementor type alias. See Traits .self: method subject. See Method Syntax (Method Calls) .static: global variable. See const and static (static)struct: structure definition. See Structs .trait: trait definition. See Traits .true: boolean true literal. See Primitive Types (Booleans) .type: type alias, and associated type definition. See type AliasesAssociated Types .unsafe: denotes unsafe code, functions, traits, and implementations. See Unsafe .use: import symbols into scope. See Crates and Modules (Importing Modules with use) .where: type constraint clauses. See Traits (where clause) .while: conditional loop. See Loops (while) .
Operators and Symbols
! (ident!(…), ident!{…}, ident![…]): denotes macro expansion. See Macros .! (!expr): bitwise or logical complement. Overloadable (Not).!= (var != expr): nonequality comparison. Overloadable (PartialEq).% (expr % expr): arithmetic remainder. Overloadable (Rem).%= (var %= expr): arithmetic remainder & assignment. Overloadable (RemAssign).& (expr & expr): bitwise and. Overloadable (BitAnd).& (&expr, &mut expr): borrow. See References and Borrowing .& (&type, &mut type, &'a type, &'a mut type): borrowed pointer type. See References and Borrowing .&= (var &= expr): bitwise and & assignment. Overloadable (BitAndAssign).&& (expr && expr): logical and.* (expr * expr): arithmetic multiplication. Overloadable (Mul).* (*expr): dereference.* (*const type, *mut type): raw pointer. See Raw Pointers .*= (var *= expr): arithmetic multiplication & assignment. Overloadable (MulAssign).+ (expr + expr): arithmetic addition. Overloadable (Add).+ (trait + trait, 'a + trait): compound type constraint. See Traits (Multiple Trait Bounds) .+= (var += expr): arithmetic addition & assignment. Overloadable (AddAssign).,: argument and element separator. See Attributes , Functions , Structs , Generics , Match , Closures , Crates and Modules (Importing Modules with use) .- (expr - expr): arithmetic subtraction. Overloadable (Sub).- (- expr): arithmetic negation. Overloadable (Neg).-= (var -= expr): arithmetic subtraction & assignment. Overloadable (SubAssign).-> (fn(…) -> type, |…| -> type): function and closure return type. See Functions , Closures .. (expr.ident): member access. See Structs , Method Syntax ... (.., expr.., ..expr, expr..expr): right-exclusive range literal... (..expr): struct literal update syntax. See Structs (Update syntax) ... (variant(x, ..), struct_type { x, .. }): "and the rest" pattern binding. See Patterns (Ignoring bindings) .... (...expr, expr...expr) in an expression : inclusive range expression. See Iterators .... (expr...expr) in a pattern : inclusive range pattern. See Patterns (Ranges) ./ (expr / expr): arithmetic division. Overloadable (Div)./= (var /= expr): arithmetic division & assignment. Overloadable (DivAssign).: (pat: type, ident: type): constraints. See Variable Bindings , Functions , Structs , Traits .: (ident: expr): struct field initializer. See Structs .: ('a: loop {…}): loop label. See Loops (Loops Labels) .;: statement and item terminator.; ([…; len]): part of fixed-size array syntax. See Primitive Types (Arrays) .<< (expr << expr): left-shift. Overloadable (Shl).<<= (var <<= expr): left-shift & assignment. Overloadable (ShlAssign).< (expr < expr): less-than comparison. Overloadable (PartialOrd).<= (var <= expr): less-than or equal-to comparison. Overloadable (PartialOrd).= (var = expr, ident = type): assignment/equivalence. See Variable Bindings , type Aliases== (var == expr): equality comparison. Overloadable (PartialEq).=> (pat => expr): part of match arm syntax. See Match .> (expr > expr): greater-than comparison. Overloadable (PartialOrd).>= (var >= expr): greater-than or equal-to comparison. Overloadable (PartialOrd).>> (expr >> expr): right-shift. Overloadable (Shr).>>= (var >>= expr): right-shift & assignment. Overloadable (ShrAssign).@ (ident @ pat): pattern binding. See Patterns (Bindings) .^ (expr ^ expr): bitwise exclusive or. Overloadable (BitXor).^= (var ^= expr): bitwise exclusive or & assignment. Overloadable (BitXorAssign).| (expr | expr): bitwise or. Overloadable (BitOr).| (pat | pat): pattern alternatives. See Patterns (Multiple patterns) .| (|…| expr): closures. See Closures .|= (var |= expr): bitwise or & assignment. Overloadable (BitOrAssign).|| (expr || expr): logical or._: "ignored" pattern binding (see Patterns (Ignoring bindings) ). Also used to make integer-literals readable (see Reference (Integer literals) ).? (expr?): Error propagation. Returns early when Err(_) is encountered, unwraps otherwise. Similar to the try! macro
'ident: named lifetime or loop label. See Lifetimes , Loops (Loops Labels) .…u8, …i32, …f64, …usize, …: numeric literal of specific type."…": string literal. See Strings .r"…", r#"…"#, r##"…"##, …: raw string literal, escape characters are not processed. See Reference (Raw String Literals) .b"…": byte string literal, constructs a [u8] instead of a string. See Reference (Byte String Literals) .br"…", br#"…"#, br##"…"##, …: raw byte string literal, combination of raw and byte string literal. See Reference (Raw Byte String Literals) .'…': character literal. See Primitive Types (char) .b'…': ASCII byte literal.|…| expr: closure. See Closures .
path<…> (e.g. Vec<u8>): specifies parameters to generic type in a type . See Generics .path::<…>, method::<…> (e.g. "42".parse::<i32>()): specifies parameters to generic type, function, or method in an expression . See Generics § Resolving ambiguities .fn ident<…> …: define generic function. See Generics .struct ident<…> …: define generic structure. See Generics .enum ident<…> …: define generic enumeration. See Generics .impl<…> …: define generic implementation.for<…> type: higher-ranked lifetime bounds.type<ident=type> (e.g. Iterator<Item=T>): a generic type where one or more associated types have specific assignments. See Associated Types .
T: U: generic parameter T constrained to types that implement U. See Traits .T: 'a: generic type T must outlive lifetime 'a. When we say that a type 'outlives' the lifetime, we mean that it cannot transitively contain any references with lifetimes shorter than 'a.T : 'static: The generic type T contains no borrowed references other than 'static ones.'b: 'a: generic lifetime 'b must outlive lifetime 'a.T: ?Sized: allow generic type parameter to be a dynamically-sized type. See Unsized Types (?Sized) .'a + trait, trait + trait: compound type constraint. See Traits (Multiple Trait Bounds) .
#[meta]: outer attribute. See Attributes .#![meta]: inner attribute. See Attributes .$ident: macro substitution. See Macros .$ident:kind: macro capture. See Macros .$(…)…: macro repetition. See Macros .
//: line comment. See Comments .//!: inner line doc comment. See Comments .///: outer line doc comment. See Comments ./*…*/: block comment. See Comments ./*!…*/: inner block doc comment. See Comments ./**…*/: outer block doc comment. See Comments .
(): empty tuple (a.k.a. unit), both literal and type.(expr): parenthesized expression.(expr,): single-element tuple expression. See Primitive Types (Tuples) .(type,): single-element tuple type. See Primitive Types (Tuples) .(expr, …): tuple expression. See Primitive Types (Tuples) .(type, …): tuple type. See Primitive Types (Tuples) .expr(expr, …): function call expression. Also used to initialize tuple structs and tuple enum variants. See Functions .ident!(…), ident!{…}, ident![…]: macro invocation. See Macros .expr.0, expr.1, …: tuple indexing. See Primitive Types (Tuple Indexing) .
{…}: block expression.Type {…}: struct literal. See Structs .
[…]: array literal. See Primitive Types (Arrays) .[expr; len]: array literal containing len copies of expr. See Primitive Types (Arrays) .[type; len]: array type containing len instances of type. See Primitive Types (Arrays) .expr[expr]: collection indexing. Overloadable (Index, IndexMut).expr[..], expr[a..], expr[..b], expr[a..b]: collection indexing pretending to be collection slicing, using Range, RangeFrom, RangeTo, RangeFull as the "index".