5 Notation

The syntax is specified using Extended Backus-Naur Form (EBNF).

Grammar: The complete formal grammar is in grammar.ebnf.

5.1 Productions

Productions are expressions terminated by .:

production_name = expression .

5.2 Operators

Notation	Meaning
a b	Sequence
a | b	Alternation
[ a ]	Optional (0 or 1)
{ a }	Repetition (0 or more)
( a )	Grouping
"x"	Literal keyword
'c'	Literal character
'a' … 'z'	Character range (inclusive)

5.3 Naming

Style	Usage
lower_case	Production names
PascalCase	Type names
snake_case	Functions, variables

5.4 Terminology

Term	Meaning
shall	Requirement (ISO/IEC Directives, Part 2)
shall not	Prohibition
should	Recommendation
may	Permission
can	Possibility or capability
error	Compile-time failure
panic	Run-time failure

5.5 Examples

EXAMPLE 1

@add (a: int, b: int) -> int = a + b;

EXAMPLE 2 The following is not valid because the return type is omitted:

@add (a: int, b: int) = a + b;  // error: missing return type