Comments and Style

Comments

-- A single-line comment
local taxRate = 0.2 -- after code

--[[
  A block comment
  spanning several lines
]]

---Returns the price including tax.
---@param price number the net price
---@return number
local function withTax(price)
  return price * (1 + taxRate)
end

print(withTax(100))

120.0

Comments starting with --- and @param/@return tags are LuaCATS annotations: lua-language-server uses them for autocompletion, hover documentation, and type checking.

Style guidelines

There's no single official style guide, but common conventions (as in the LuaRocks and Olivine Labs guides) are:

• local for everything; avoid globals.
• Two-space indentation (four is also common).
• snake_case or camelCase for variables and functions — consistently; PascalCase for classes and modules that act like classes.
• UPPER_CASE for constants.
• _ for values you ignore.
• Double quotes for strings (single quotes when the text contains double quotes).
• Keep functions small; return early instead of nesting ifs.

Tools

• StyLua — formats code automatically.
• luacheck — warns about globals, unused variables, and shadowing.
• lua-language-server — errors and type hints in your editor.

What's next

You now know the core of Lua. Try the Beginner Projects, then continue to Level 2 — Intermediate, which starts with closures.