Ask the right questions to secure the right Lua talent among an increasingly shrinking pool of talent.

Lua is a powerful, efficient, lightweight, and embeddable scripting language, first developed in 1993 by Roberto Ierusalimschy, Luiz Henrique de Figueiredo, and Waldemar Celes at the Pontifical Catholic University of Rio de Janeiro, Brazil. It was designed with a focus on simplicity, small size, and portability with extensible semantics. Lua's design is noted for its minimalism and flexibility, often used for scripting in games and web applications. It is cross-platform, with interpreters available for various operating systems. Lua's popularity in the gaming industry is exemplified by its adoption in major titles like World of Warcraft and Angry Birds.

First 20 minutes

General Lua knowledge and experience

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

How would you implement error handling in Lua?

Error handling in Lua can be implemented using the pcall function, which executes a function in protected mode and catches any errors.

What is the difference between local and global variables in Lua?

Local variables have their scope limited to the block where they are declared. Global variables don't have a specific scope and can be accessed from anywhere in the code.

How would you create a function in Lua?

You can create a function in Lua using the function keyword. For example, 'function myFunction() end'.

What are the basic data types in Lua?

The basic data types in Lua are nil, boolean, number, string, userdata, function, thread, and table.

How would you declare a variable in Lua?

You can declare a variable in Lua using the local keyword followed by the variable name. For example, 'local x'.

The hiring guide has been successfully sent to your email address.

Oops! Something went wrong while submitting the form.

What youre looking for early-on

Does the candidate have a solid understanding of software development principles and practices?

This is crucial for writing clean, maintainable, and efficient code.

Has the candidate shown an ability to learn new technologies quickly?

The tech industry is always evolving, so it's important for a developer to be able to learn and adapt quickly.

Does the candidate have experience with Lua libraries and frameworks?

Knowledge of libraries and frameworks can speed up development time and make the candidate more productive.

Can the candidate work well in a team environment?

Software development often involves teamwork. A candidate who can work well with others will be more effective.

Has the candidate demonstrated problem-solving skills during the interview?

This is crucial as programming involves a lot of problem-solving and the candidate should be able to handle complex scenarios.

Does the candidate have a strong understanding of the Lua programming language?

This is important because the candidate will need to write, debug, and understand Lua code as a part of their job.

Next 20 minutes

Specific Lua development questions

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

How would you implement inheritance in Lua?

Inheritance in Lua can be implemented using metatables. The metatable of the derived class points to the base class, allowing the derived class to access the base class's methods.

What is the use of the '#' operator in Lua?

The '#' operator is used to get the length of a string or the number of elements in a table.

How would you create a table in Lua?

You can create a table in Lua using the {} syntax. For example, 'local myTable = {}'.

Describe the difference between pairs and ipairs in Lua.

Pairs iterates over all elements in the table, while ipairs iterates only over the integer indexes of a table.

What are metatables in Lua?

Metatables in Lua are tables that can change the behavior of the original table. They can define how an object behaves in arithmetic operations, comparisons, concatenation, length operation, etc.

The hiring guide has been successfully sent to your email address.

Oops! Something went wrong while submitting the form.

At this point, a skilled Lua engineer should demonstrate proficiency in Lua programming and scripting, problem-solving skills, and knowledge of data structures and algorithms. Red flags include lack of debugging skills, inability to explain complex concepts, and unfamiliarity with Lua's unique features.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with Lua.

What does the following Lua code do?print(type('Hello world'))
This code prints the type of 'Hello world', which is a string.
What will be the output of the following Lua code?x = 10
y = 20
print(x == y)
The code compares the values of x and y. Since 10 is not equal to 20, it will print 'false'.
What does the following Lua code do?t = {4, 5, 6}
table.insert(t, 1, 3)
print(t[1])
This code creates a table (array) 't' with elements 4, 5, 6. Then it inserts the number 3 at the first position of the table. Finally, it prints the first element of the table, which is 3.
What does the following Lua code do?co = coroutine.create(function () print('hello') end)
coroutine.resume(co)
This code creates a coroutine that prints 'hello' when it is resumed. The coroutine is then resumed, so it will print 'hello'.
What does the following Lua code do?Account = {}
Account.__index = Account
function Account.create(balance)
  local acc = {}
  setmetatable(acc, Account)
  acc.balance = balance
  return acc
end
This code defines a simple class 'Account' with a create function. The create function is used to create new instances of the Account class. It sets the balance of the account and returns the new account object.
What does the following Lua code do?function fib(n)
  if n < 2 then return n end
  return fib(n - 1) + fib(n - 2)
end
print(fib(10))
This code defines a recursive function to calculate the Fibonacci number at a given position 'n'. It then prints the 10th Fibonacci number, which is 55.

Wrap-up questions

Final candidate for Lua role questions

The final few interview questions for a Lua candidate should typically focus on a combination of technical skills, personal goals, growth potential, team dynamics, and company culture.

How would you implement a module in Lua?

A module in Lua is implemented as a table. Functions and variables are defined as fields in the table. The module can then be included in other scripts using the require function.

What is tail call optimization in Lua?

Tail call optimization in Lua is a feature where a function call is the final action in another function, the latter function's stack frame can be reused, saving memory.

How would you write a recursive function in Lua?

A recursive function in Lua is a function that calls itself. For example, a function to calculate the factorial of a number could be written recursively.

Describe the difference between the '==' and '===' operators in Lua.

Lua only has the '==' operator for equality comparison. The '===' operator does not exist in Lua.

What are coroutines in Lua?

Coroutines are a kind of lightweight threads that don't share state with other coroutines. They are used for non-preemptive multitasking.

The hiring guide has been successfully sent to your email address.

Oops! Something went wrong while submitting the form.

Lua application related

Product Perfect's Lua development capabilities

Beyond hiring for your Lua engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in Lua projects, and can engage in multiple capacities.

Lua Consultive assessments

Lua Application Conversion Assessment Lua Application Integration Assessment Lua Data & Database Integration Assessment

Custom Lua development projects

Custom Lua App Conversion Lua Custom App Development Process App UI Design for Lua Facelifts

Lua Developer Hiring Guide

Hiring Guide for Lua Engineers

First 20 minutes

General Lua knowledge and experience

How would you implement error handling in Lua?

What is the difference between local and global variables in Lua?

How would you create a function in Lua?

What are the basic data types in Lua?

How would you declare a variable in Lua?

What youre looking for early-on

Does the candidate have a solid understanding of software development principles and practices?

Has the candidate shown an ability to learn new technologies quickly?

Does the candidate have experience with Lua libraries and frameworks?

Can the candidate work well in a team environment?

Has the candidate demonstrated problem-solving skills during the interview?

Does the candidate have a strong understanding of the Lua programming language?

Next 20 minutes

Specific Lua development questions

How would you implement inheritance in Lua?

What is the use of the '#' operator in Lua?

How would you create a table in Lua?

Describe the difference between pairs and ipairs in Lua.

What are metatables in Lua?

The ideal back-end app developer

What you’re looking to see on the Lua engineer at this point.

What does the following Lua code do?

This code prints the type of 'Hello world', which is a string.

What will be the output of the following Lua code?

The code compares the values of x and y. Since 10 is not equal to 20, it will print 'false'.

What does the following Lua code do?

This code creates a table (array) 't' with elements 4, 5, 6. Then it inserts the number 3 at the first position of the table. Finally, it prints the first element of the table, which is 3.

What does the following Lua code do?

This code creates a coroutine that prints 'hello' when it is resumed. The coroutine is then resumed, so it will print 'hello'.

What does the following Lua code do?

This code defines a simple class 'Account' with a create function. The create function is used to create new instances of the Account class. It sets the balance of the account and returns the new account object.

What does the following Lua code do?

This code defines a recursive function to calculate the Fibonacci number at a given position 'n'. It then prints the 10th Fibonacci number, which is 55.

Wrap-up questions

Final candidate for Lua role questions

How would you implement a module in Lua?

What is tail call optimization in Lua?

How would you write a recursive function in Lua?

Describe the difference between the '==' and '===' operators in Lua.

What are coroutines in Lua?

Lua Consultive assessments

Custom Lua development projects