zig/doc/langref.md

Language Reference

Primitive Numeric Types:

zig	C equivalent	Description
bool	bool	unsigned 1-bit integer
i8	int8_t	signed 8-bit integer
u8	uint8_t	unsigned 8-bit integer
i16	int16_t	signed 16-bit integer
u16	uint16_t	unsigned 16-bit integer
i32	int32_t	signed 32-bit integer
u32	uint32_t	unsigned 32-bit integer
i64	int64_t	signed 64-bit integer
u64	uint64_t	unsigned 64-bit integer
f32	float	32-bit IEE754 floating point
f64	double	64-bit IEE754 floating point
f128	long double	128-bit IEE754 floating point
isize	intptr_t	signed pointer sized integer
usize	uintptr_t	unsigned pointer sized integer
c_short	short	for API compatibility with C
c_ushort	unsigned short	for API compatibility with C
c_int	int	for API compatibility with C
c_uint	unsigned int	for API compatibility with C
c_long	long	for API compatibility with C
c_ulong	unsigned long	for API compatibility with C
c_longlong	long long	for API compatibility with C
c_ulonglong	unsigned long long	for API compatibility with C

Grammar

Root : many(TopLevelDecl) token(EOF)

TopLevelDecl : FnDef | ExternBlock | RootExportDecl | Import | ContainerDecl | VariableDeclaration

VariableDeclaration : option(FnVisibleMod) (token(Var) | token(Const)) token(Symbol) (token(Eq) Expression | token(Colon) PrefixOpExpression option(token(Eq) Expression))

ContainerDecl : many(Directive) option(FnVisibleMod) (token(Struct) | token(Enum)) token(Symbol) token(LBrace) many(StructMember) token(RBrace)

StructMember: StructField | FnDecl

StructField : token(Symbol) option(token(Colon) Expression) token(Comma))

Import : many(Directive) token(Import) token(String) token(Semicolon)

RootExportDecl : many(Directive) token(Export) token(Symbol) token(String) token(Semicolon)

ExternBlock : many(Directive) token(Extern) token(LBrace) many(FnDecl) token(RBrace)

FnProto : many(Directive) option(FnVisibleMod) token(Fn) token(Symbol) ParamDeclList option(PrefixOpExpression)

Directive : token(NumberSign) token(Symbol) token(LParen) token(String) token(RParen)

FnVisibleMod : token(Pub) | token(Export)

FnDecl : FnProto token(Semicolon)

FnDef : FnProto token(FatArrow) Block

ParamDeclList : token(LParen) list(ParamDecl, token(Comma)) token(RParen)

ParamDecl : option(token(NoAlias)) token(Symbol) token(Colon) PrefixOpExpression | token(Ellipsis)

Block : token(LBrace) list(option(Statement), token(Semicolon)) token(RBrace)

Statement : Label | VariableDeclaration token(Semicolon) | NonBlockExpression token(Semicolon) | BlockExpression

Label: token(Symbol) token(Colon)

Expression : BlockExpression | NonBlockExpression

NonBlockExpression : ReturnExpression | AssignmentExpression

AsmExpression : token(Asm) option(token(Volatile)) token(LParen) token(String) option(AsmOutput) token(RParen)

AsmOutput : token(Colon) list(AsmOutputItem, token(Comma)) option(AsmInput)

AsmInput : token(Colon) list(AsmInputItem, token(Comma)) option(AsmClobbers)

AsmOutputItem : token(LBracket) token(Symbol) token(RBracket) token(String) token(LParen) (token(Symbol) | token(Arrow) PrefixOpExpression) token(RParen)

AsmInputItem : token(LBracket) token(Symbol) token(RBracket) token(String) token(LParen) Expression token(RParen)

AsmClobbers: token(Colon) list(token(String), token(Comma))

UnwrapMaybeExpression : BoolOrExpression token(DoubleQuestionMark) BoolOrExpression | BoolOrExpression

AssignmentExpression : UnwrapMaybeExpression AssignmentOperator UnwrapMaybeExpression | UnwrapMaybeExpression

AssignmentOperator : token(Eq) | token(TimesEq) | token(DivEq) | token(ModEq) | token(PlusEq) | token(MinusEq) | token(BitShiftLeftEq) | token(BitShiftRightEq) | token(BitAndEq) | token(BitXorEq) | token(BitOrEq) | token(BoolAndEq) | token(BoolOrEq) 

BlockExpression : IfExpression | Block | WhileExpression

WhileExpression : token(While) token(LParen) Expression token(RParen) Expression

BoolOrExpression : BoolAndExpression token(BoolOr) BoolOrExpression | BoolAndExpression

ReturnExpression : token(Return) option(Expression)

IfExpression : IfVarExpression | IfBoolExpression

IfBoolExpression : token(If) token(LParen) Expression token(RParen) Expression option(Else)

IfVarExpression : token(If) token(LParen) (token(Const) | token(Var)) token(Symbol) option(token(Colon) PrefixOpExpression) Token(MaybeAssign) Expression token(RParen) Expression Option(Else)

Else : token(Else) Expression

BoolAndExpression : ComparisonExpression token(BoolAnd) BoolAndExpression | ComparisonExpression

ComparisonExpression : BinaryOrExpression ComparisonOperator BinaryOrExpression | BinaryOrExpression

ComparisonOperator : token(BoolEq) | token(BoolNotEq) | token(BoolLessThan) | token(BoolGreaterThan) | token(BoolLessEqual) | token(BoolGreaterEqual)

BinaryOrExpression : BinaryXorExpression token(BinOr) BinaryOrExpression | BinaryXorExpression

BinaryXorExpression : BinaryAndExpression token(BinXor) BinaryXorExpression | BinaryAndExpression

BinaryAndExpression : BitShiftExpression token(Ampersand) BinaryAndExpression | BitShiftExpression

BitShiftExpression : AdditionExpression BitShiftOperator BitShiftExpression | AdditionExpression

BitShiftOperator : token(BitShiftLeft) | token(BitShiftRight)

AdditionExpression : MultiplyExpression AdditionOperator AdditionExpression | MultiplyExpression

AdditionOperator : token(Plus) | token(Minus)

MultiplyExpression : CurlySuffixExpression MultiplyOperator MultiplyExpression | CurlySuffixExpression

CurlySuffixExpression : PrefixOpExpression option(ContainerInitExpression)

MultiplyOperator : token(Star) | token(Slash) | token(Percent)

PrefixOpExpression : PrefixOp PrefixOpExpression | SuffixOpExpression

SuffixOpExpression : PrimaryExpression option(FnCallExpression | ArrayAccessExpression | FieldAccessExpression | SliceExpression)

FieldAccessExpression : token(Dot) token(Symbol)

FnCallExpression : token(LParen) list(Expression, token(Comma)) token(RParen)

ArrayAccessExpression : token(LBracket) Expression token(RBracket)

SliceExpression : token(LBracket) Expression token(Ellipsis) option(Expression) token(RBracket) option(token(Const))

ContainerInitExpression : token(LBrace) ContainerInitBody token(RBrace)

ContainerInitBody : list(StructLiteralField, token(Comma)) | list(Expression, token(Comma))

StructLiteralField : token(Dot) token(Symbol) token(Eq) Expression

PrefixOp : token(Not) | token(Dash) | token(Tilde) | token(Star) | (token(Ampersand) option(token(Const))) | token(QuestionMark)

PrimaryExpression : token(Number) | token(String) | token(CharLiteral) | KeywordLiteral | GroupedExpression | GotoExpression | BlockExpression | token(Symbol) | (token(AtSign) token(Symbol) FnCallExpression) | ArrayType | AsmExpression

ArrayType : token(LBracket) option(Expression) token(RBracket) option(token(Const)) PrefixOpExpression

GotoExpression: token(Goto) token(Symbol)

GroupedExpression : token(LParen) Expression token(RParen)

KeywordLiteral : token(True) | token(False) | token(Null) | token(Break) | token(Continue)

Operator Precedence

x() x[] x.y
!x -x ~x *x &x ?x
x{}
* / %
+ -
<< >>
&
^
|
== != < > <= >=
&&
||
??
= *= /= %= += -= <<= >>= &= ^= |= &&= ||=

Literals

Characters and Strings

            | Example  | Characters  | Escapes        | Null Term | Type

----------------|----------|-------------|----------------|-----------|---------- Byte | 'H' | All ASCII | Byte | No | u8 UTF-8 Bytes | "hello" | All Unicode | Byte & Unicode | No | [5; u8] UTF-8 C string | c"hello" | All Unicode | Byte & Unicode | Yes | *const u8

Byte Escapes

  | Name

------|---------------------------------------- \x7F | 8-bit character code (exactly 2 digits) \n | Newline \r | Carriage return \t | Tab \ | Backslash \0 | Null ' | Single quote " | Double quote

Unicode Escapes

      | Name

----------|----------------------------------------------- \u{7FFF} | 24-bit Unicode character code (up to 6 digits)

Numbers

Number literals	Example	Exponentiation
Decimal integer	98222	N/A
Hex integer	0xff	N/A
Octal integer	0o77	N/A
Binary integer	0b11110000	N/A
Floating-point	123.0E+77	Optional
Hex floating point	TODO	TODO