Hiring guide for Hack Engineers

Hack Developer Hiring Guide

Hacking is the act of exploiting a computer system or a computer network to gain unauthorized access. This can be done through a variety of methods, including exploiting software vulnerabilities, social engineering, or physical access to the system. The term "hacking" has a long history, dating back to the early days of computing. In the 1960s, the term was used to describe hobbyists who enjoyed experimenting with and modifying computer systems. Today, hacking is often associated with malicious activity, such as cybercrime. However, there are also many legitimate uses for hacking, such as penetration testing and security research.

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

First 20 minutes

General Hack app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in Hack application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you define the Hack programming language?
Hack is a programming language for the HipHop Virtual Machine (HHVM), created by Facebook as a dialect of PHP. It is designed to be safe, fast, and to allow developers to use both dynamic and static typing.
What are the key features of Hack?
Hack has several key features including static typing, type inference, generics, nullable types, collections, and asynchronous programming support.
Describe the difference between Hack and PHP.
While Hack is a dialect of PHP, it introduces static typing and other features not available in PHP. Hack also supports asynchronous programming, which PHP does not natively support.
How would you handle errors in Hack?
Hack uses exceptions to handle errors. You can use try-catch blocks to catch exceptions and handle them appropriately.
What are generics in Hack and how would you use them?
Generics in Hack allow classes and methods to operate with different types. They are a way of creating reusable code. You can use them by defining a class or method with a type parameter, and then use that type parameter in the body of the class or method.
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What you’re looking for early on

Does the candidate have a strong understanding of Hack language?
Can the candidate solve complex problems?
Is the candidate able to communicate effectively?
Does the candidate have experience with other programming languages?

Next 20 minutes

Specific Hack development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

How would you implement asynchronous programming in Hack?
Hack provides the async keyword to declare asynchronous functions, and the await keyword to pause execution until an asynchronous operation completes. You can use these keywords to write non-blocking code.
What are nullable types in Hack and how would you use them?
Nullable types in Hack are types that can also be null. You can use them by prefixing a type with a question mark. This indicates that the value can be of the specified type, or it can be null.
Describe the difference between collections and arrays in Hack.
Collections in Hack are a replacement for arrays. They provide a more consistent and powerful API than arrays. Unlike arrays, collections are always objects, and they have a number of methods that can be used to manipulate them.
How would you use lambda expressions in Hack?
Lambda expressions in Hack are anonymous functions that can be used as values. You can use them by using the ==> operator to define the function, and then passing it as a parameter to another function.
What are shapes in Hack and how would you use them?
Shapes in Hack are a way of defining complex data structures. They are similar to arrays, but they allow you to specify the keys and their types. You can use them by using the shape keyword to define the structure, and then using the keys to access the values.
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The ideal back-end app developer

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

At this point, a skilled Hack engineer should demonstrate strong problem-solving abilities, proficiency in Hack programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

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

What does the following Hack code do?
function add(int $x, int $y): int {
  return $x + $y;
This code defines a function named 'add' that takes two integer parameters, adds them together, and returns the result.
What will be the output of the following Hack code?
echo Str\strip_prefix('Hacklang', 'Hack');
The output of this code will be 'lang'. The function 'strip_prefix' removes the specified prefix 'Hack' from the string 'Hacklang'.
What does the following Hack code do?
$numbers = vec[1, 2, 3, 4, 5];
$sum = C\reduce($numbers, ($a, $b) ==> $a + $b);
This code creates a vector of numbers and then uses the 'reduce' function to sum all the numbers in the vector. The result is stored in the variable 'sum'.
What does the following Hack code do?
async function get_data(): Awaitable {
  return await SleepWaitHandle::create(1000);
This code defines an asynchronous function named 'get_data' that returns an 'Awaitable' of type int. The function creates a new 'SleepWaitHandle' that pauses execution for 1000 milliseconds before returning.

Wrap-up questions

Final candidate for Hack Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle Hack application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

How would you use XHP in Hack?
XHP in Hack is a way of embedding XML-like fragments in your code. You can use it by defining an XHP class, and then using it in your code like an XML element.
What are the benefits of using Hack over other programming languages?
Hack combines the best features of static and dynamic typing, and it has powerful features like generics, nullable types, and asynchronous programming. It also has a fast runtime thanks to the HipHop Virtual Machine.
How would you optimize a Hack application for performance?
You can optimize a Hack application by using static typing to avoid runtime type checks, using collections instead of arrays for better performance, and using asynchronous programming to avoid blocking operations.

Hack application related

Product Perfect's Hack development capabilities

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