Lexical Structure

2. Lexical Structure
   • Identifiers
   • Keywords
   • Literals
   • Operators
   • Delimiters

2. Lexical Structure #

2.1 Identifiers #

Identifiers must start with a letter or underscore, followed by letters, digits, or underscores:

ID := [a-zA-Z_][a-zA-Z0-9_]*

2.2 Keywords #

Reserved keywords:

fn let mut type import match if then else case of extern

2.3 Literals #

Integer Literals #

INTEGER := [0-9]+

String Literals #

STRING := '"' (CHAR | ESCAPE_SEQUENCE)* '"'
ESCAPE_SEQUENCE := '\n' | '\t' | '\r' | '\\' | '\"'

Interpolated String Literals #

INTERPOLATED_STRING := '"' (CHAR | INTERPOLATION)* '"'
INTERPOLATION := '${' EXPRESSION '}'

Immutable List Literals #

LIST := '[' (expression (',' expression)*)? ']'

Examples:

let numbers = [1, 2, 3, 4]  // Fixed size: 4 elements
let names = ["Alice", "Bob", "Charlie"]  // Fixed size: 3 elements
let pair = [x, y]  // Fixed size: 2 elements

2.4 Operators #

Arithmetic Operators (All Safe by Default) #

• + Addition: (Int, Int) -> Result<Int, MathError>
• - Subtraction: (Int, Int) -> Result<Int, MathError>
• * Multiplication: (Int, Int) -> Result<Int, MathError>
• / Division: (Int, Int) -> Result<Int, MathError>

CRITICAL: All arithmetic operators return Result types to handle overflow, underflow, and division by zero.

Assignment Operator #

• = Assignment

Other Operators #

• => Lambda/Match arm arrow
• | Union type separator
• :: Type annotation

2.5 Delimiters #

• ( ) Parentheses
• { } Braces
• [ ] Brackets
• , Comma
• : Colon
• ; Semicolon
• . Dot