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2. Lexical Structure

Comments and Docstrings

Line comments in vv start with // and continue to the end of the line.

// This is a comment

Docstrings are special comments that start with ///. They are used to document modules, variables, and functions. Docstrings must be placed immediately before the declaration they describe.

Module Docstring

A module docstring must be at the very top of the file, before any imports or declarations.

/// This module provides utility functions for mathematical operations.
/// It is the entry point for the math library.

import console from "std/console.vv"

Variable Docstring

Place a docstring immediately before a let declaration.

/// The current version of the application.
let version = "1.2.3"

Function Docstring

Place a docstring immediately before a fun declaration. You can also use tags like @param or @return within the docstring for clearer documentation.

/// Calculates the area of a circle.
/// @param radius The radius of the circle.
/// @return The calculated area.
fun calculate_area(radius)
    return 3.14159 * radius * radius
end

Multilingual Docstrings

Docstrings can support multiple languages within a single block. By default, docstrings are associated with the en (English) language. You can switch the language for subsequent lines using the @lang <code> tag.

/// @lang en
/// Returns the sum of two numbers.
/// @lang jp
/// 2つの数値の合計を返します。
fun add(a, b)
    return a + b
end

Identifiers

Identifiers are used to name variables, functions, and parameters. They must start with a letter or underscore, followed by any number of letters, digits, or underscores.

Keywords

The following keywords are reserved and cannot be used as identifiers: