Lexical Structure

Identifiers

Start with letter or underscore, followed by letters, digits, or underscores.

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

fn let mut type match extern import module where
effect perform handle in
spawn await yield select

INTEGER := [0-9]+

Examples:

let count = 42
let negative = -17
let zero = 0

FLOAT := [0-9]+ '.' [0-9]+ ([eE] [+-]? [0-9]+)?
       | [0-9]+ [eE] [+-]? [0-9]+

Examples:

let pi = 3.14159
let temperature = -273.15
let scientific = 6.022e23
let small = 1.5e-10

Type Inference:

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

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

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

let numbers = [1, 2, 3, 4]
let names   = ["Alice", "Bob", "Charlie"]
let pair    = [x, y]

+, -, *, /, %. All arithmetic returns Result; full signatures and semantics are in Error Handling.