Input & Output

Let’s start exploring Lune’s capabilities with the stdio library, which handles standard input and output. This is one of the most useful libraries for creating interactive scripts.

Getting User Input

The stdio library makes it easy to interact with users. Let’s create our first interactive script called hello.luau:

hello.luau

local stdio = require("@lune/stdio")

local name = stdio.prompt("text", "What's your name?")

print(`Hello, {name}!`)

Save this file in your current directory, then run it using the Lune CLI:

Terminal

lune run hello

When you run this script, it will wait for you to type your name and press Enter, then greet you!

Different Types of Prompts

The stdio library can prompt for more than just text. Let’s expand our script to ask a yes/no question:

hello.luau

local stdio = require("@lune/stdio")

local name = stdio.prompt("text", "What's your name?")
print(`Hello, {name}!`)

local confirmed = stdio.prompt("confirm", "Is that really your name?")
if confirmed then
  print(`Nice to meet you, {name}!`)
  print("Have a great day!")
else
  print("Hmm, well whoever you are, welcome!")
end

The confirm prompt type shows a yes/no question and returns true or false based on the user’s choice.

These two prompt types - text and confirm - will cover most of your interactive script needs. There are more advanced options available in the stdio API reference when you need them.

Extra: Number Guessing Game

Building a Simple Game

Here’s a fun example that combines what we’ve learned with some basic Luau programming. Don’t worry if you don’t understand every line yet - focus on how stdio.prompt is used to create an interactive experience:

guessing-game.luau

local stdio = require("@lune/stdio")

print("Welcome to the number guessing game!")
print("I'm thinking of a number between 1 and 10.")
print()

local answer = tostring(math.random(1, 10))
local attempts = 0

local guess = stdio.prompt("text", "What's your guess?")
attempts += 1

while guess ~= answer do
  if tonumber(guess) and tonumber(guess) < tonumber(answer) then
    print("Too low! Try again.")
  elseif tonumber(guess) and tonumber(guess) > tonumber(answer) then
    print("Too high! Try again.")
  else
    print("That's not a valid number.")
  end

  guess = stdio.prompt("text", "What's your guess?")
  attempts += 1
end

print()
print(`Correct! You got it in {attempts} attempts!`)

Try running this game and see if you can guess the number! This example shows how stdio.prompt can be used in a loop to create ongoing interaction.

Terminal

lune run guessing-game

What’s Next?

Now that you know how to get input from users, let’s learn about handling input that comes from the command line when someone runs your script. This is covered in the next chapter on Arguments.