A Practical Introduction to Lua (Beginner Friendly)

Leeting Yan

Lua is a lightweight, embeddable scripting language widely used in game engines (Defold, Roblox, Corona), configuration systems, automation tools, and embedded platforms.

This article gives you a clean, beginner-friendly introduction with complete and runnable examples.

1. Setting Up and Running Lua

Install Lua

  • macOS
brew install lua
  • Linux (Ubuntu/Debian)
sudo apt-get install lua5.4
  • Windows
    Download binaries or use Lua for Windows.

Run a Script

Write hello.lua:

print("Hello, Lua!")

Run:

lua hello.lua

Enter interactive REPL:

lua
> print("Hello REPL")

2. Basic Syntax and Data Types

Comments

-- single-line comment

--[[
multi-line
comment
]]

Variables

x = 10        -- global
local y = 20  -- local

print(x, y)

Core Types

  • nil
  • boolean
  • number
  • string
  • table (Lua’s all-purpose structure)
  • function

Numbers & Operators

local a, b = 10, 3

print(a + b)
print(a - b)
print(a * b)
print(a / b)
print(a % b)
print(a ^ b)   -- exponent

Strings

local s1 = "Hello"
local s2 = 'Lua'

local s3 = [[
Multi-line
string
]]

print(s1 .. ", " .. s2 .. "!")  -- concatenation
print(#s1)                      -- length

3. Tables: Arrays, Dictionaries, Objects

Tables are the heart of Lua.

Arrays

local arr = {10, 20, 30}

print(arr[1])
print(arr[2])
print(arr[3])

Dictionaries

local person = {
  name = "Alice",
  age  = 25
}

print(person.name)
print(person["age"])

Mixed Usage

local t = {
  100, 200,
  name = "Bob",
  score = 95
}

print(t[1], t.name, t.score)

4. Control Flow

if / elseif / else

local score = 88

if score >= 90 then
  print("A")
elseif score >= 80 then
  print("B")
else
  print("C or below")
end

while

local i = 1
while i <= 3 do
  print(i)
  i = i + 1
end

repeat … until

local n = 1
repeat
  print(n)
  n = n + 1
until n > 3

for numeric loop

for i = 1, 5 do
  print(i)
end

for generic loop

Iterate array

local arr = {"Lua", "Python", "Go"}

for i, v in ipairs(arr) do
  print(i, v)
end

Iterate dictionary

local config = {host="127.0.0.1", port=8080}

for k, v in pairs(config) do
  print(k, v)
end

5. Functions

Basic Function

local function add(a, b)
  return a + b
end

print(add(3, 5))

Multiple Return Values

local function divide(a, b)
  if b == 0 then
    return nil, "division by zero"
  end
  return a / b, nil
end

local v, err = divide(10, 0)
print(v, err)

Anonymous Function

local result = (function(x, y)
  return x * y
end)(3, 4)

print(result)

6. Modules

Create math_utils.lua:

local M = {}

function M.add(a, b)
  return a + b
end

function M.sub(a, b)
  return a - b
end

return M

Use it:

local m = require("math_utils")

print(m.add(1, 2))
print(m.sub(5, 3))

7. Simple Object-Oriented Style

Lua uses tables + metatables to simulate objects.

local Person = {}
Person.__index = Person

function Person:new(name, age)
  local obj = {name=name, age=age}
  setmetatable(obj, self)
  return obj
end

function Person:say()
  print("Hi, I'm " .. self.name)
end

local p = Person:new("Alice", 25)
p:say()

8. Useful Standard Libraries

String

local s = "hello lua"
print(string.upper(s))
print(string.sub(s, 1, 5))

Math

math.randomseed(os.time())
print(math.random(1, 10))

Table

local t = {}
table.insert(t, "Lua")
table.insert(t, "is fun")
print(table.concat(t, " "))

9. Mini Example: Simple CLI Todo Tool

Save as todo.lua:

local todos = {}

local function add(text)
  table.insert(todos, text)
  print("Added:", text)
end

local function list()
  if #todos == 0 then
    print("No todos.")
    return
  end
  for i, v in ipairs(todos) do
    print(i .. ". " .. v)
  end
end

print("Lua Todo CLI")
while true do
  io.write("> ")
  local line = io.read("*l")
  if line == "quit" then break end
  if line == "list" then
    list()
  elseif line:sub(1,3) == "add" then
    add(line:sub(5))
  else
    print("Commands: add <text>, list, quit")
  end
end

Run:

lua todo.lua

10. Next Steps

After mastering this introduction, continue with:

  • Metatables & metamethods (__index, __add, etc.)
  • Coroutines
  • LuaRocks package manager
  • Using Lua in engines (Defold, LÖVE)