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Numeric types Integer types The unsigned integer types consist of: Type | Minimum | Maximum -------|---------|------------------- u8 | 0 | 28-1 u16 | 0 | 216-1 u32 | 0 | 232-1 u64 | 0 | 264-1 u128 | 0 | 2128-1 The signed two's complement in...
Boolean type let b: bool = true; The boolean type or bool is a primitive data type that can take on one of two values, called true and false. Values of this type may be created using a literal expression using the keywords true and false co...
Types Every variable, item, and value in a Rust program has a type. The type of a value defines the interpretation of the memory holding it and the operations that may be performed on the value. Built-in types are tightly integrated into th...
Patterns Pattern -> `|`? PatternNoTopAlt ( `|` PatternNoTopAlt )* PatternNoTopAlt -> PatternWithoutModernRange | ModernRangePattern PatternWithoutModernRange -> LiteralPattern | IdentifierPattern | WildcardPattern | RestPattern | ReferenceP...
_ expressions UnderscoreExpression -> `_` Underscore expressions, denoted with the symbol _, are used to signify a placeholder in a destructuring assignment. They may only appear in the left-hand side of an assignment. Note that this is dis...
Await expressions AwaitExpression -> Expression `.` `await` An await expression is a syntactic construct for suspending a computation provided by an implementation of std::future::IntoFuture until the given future is ready to produce a valu...
return expressions ReturnExpression -> `return` Expression? Return expressions are denoted with the keyword return. Evaluating a return expression moves its argument into the designated output location for the current function call, destroy...
match expressions MatchExpression -> `match` Scrutinee `{` InnerAttribute* MatchArms? `}` Scrutinee -> Expression _except [StructExpression]_ MatchArms -> ( MatchArm `=>` ( ExpressionWithoutBlock `,` | ExpressionWithBlock `,`? ) )* MatchArm...
if expressions IfExpression -> `if` Conditions BlockExpressionNoInnerAttributes (`else` ( BlockExpressionNoInnerAttributes | IfExpression ) )? Conditions -> Expression _except [StructExpression]_ | LetChain LetChain -> LetChainCondition ( `...
Range expressions RangeExpression -> RangeExpr | RangeFromExpr | RangeToExpr | RangeFullExpr | RangeInclusiveExpr | RangeToInclusiveExpr RangeExpr -> Expression `..` Expression RangeFromExpr -> Expression `..` RangeToExpr -> `..` Expression...
Loops and other breakable expressions LoopExpression -> LoopLabel? ( InfiniteLoopExpression | PredicateLoopExpression | IteratorLoopExpression | LabelBlockExpression ) Rust supports four loop expressions: • A loop expression denotes an infi...
Closure expressions ClosureExpression -> `async`?[^cl-async-edition] `move`? ( `||` | `|` ClosureParameters? `|` ) (Expression | `->` TypeNoBounds BlockExpression) ClosureParameters -> ClosureParam (`,` ClosureParam)* `,`? ClosureParam -> O...
Field access expressions FieldExpression -> Expression `.` IDENTIFIER A field expression is a place expression that evaluates to the location of a field of a struct or union. When the operand is mutable, the field expression is also mutable...
Method-call expressions MethodCallExpression -> Expression `.` PathExprSegment `(`CallParams? `)` A method call consists of an expression (the receiver) followed by a single dot, an expression path segment, and a parenthesized expression-li...
Call expressions CallExpression -> Expression `(` CallParams? `)` CallParams -> Expression ( `,` Expression )* `,`? A call expression calls a function. The syntax of a call expression is an expression, called the function operand, followed...
Struct expressions StructExpression -> PathInExpression `{` (StructExprFields | StructBase)? `}` StructExprFields -> StructExprField (`,` StructExprField)* (`,` StructBase | `,`?) StructExprField -> OuterAttribute* ( IDENTIFIER | (IDENTIFIE...
Tuple and tuple indexing expressions Tuple expressions TupleExpression -> `(` TupleElements? `)` TupleElements -> ( Expression `,` )+ Expression? A tuple expression constructs tuple values. The syntax for tuple expressions is a parenthesize...
Array and array index expressions Array expressions ArrayExpression -> `[` ArrayElements? `]` ArrayElements -> Expression ( `,` Expression )* `,`? | Expression `;` Expression Array expressions construct arrays. Array expressions come in two...
Grouped expressions GroupedExpression -> `(` Expression `)` A parenthesized expression wraps a single expression, evaluating to that expression. The syntax for a parenthesized expression is a (, then an expression, called the enclosed opera...
"You don't declare lifetimes. Lifetimes come from the shape of your code, so to change what the lifetimes are, you must change the shape of the code."