Julia Developer Hiring Guide

Hiring Guide for Julia Engineers

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

Julia is a high-level, high-performance programming language designed for technical computing, with syntax that is familiar to users of other technical computing environments. Introduced in 2012 by a team of four individuals - Viral B. Shah, Alan Edelman, Jeff Bezanson, and Stefan Karpinski - it aims to address the need for an expressive and efficient language for data manipulation and computation. Julia provides parallel computing capabilities out of the box and unlimited scalability with minimal effort. It has been utilized in a diverse range of applications including machine learning, scientific computing, and data science. The language's development and maintenance are managed by the Julia Computing company.

First 20 minutes

General Julia 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.

What are Macros in Julia and how would you use them?

Macros in Julia provide a method to include generated code in the final body of a program. A macro maps a tuple of arguments to a returned expression, and the resulting expression is compiled directly. This allows programmers to generate code programmatically, and to define custom language constructs.

How would you handle missing values in Julia?

In Julia, missing values are handled using the 'missing' keyword. If a value is missing in a computation, the result is generally 'missing'. You can also use the 'ismissing()' function to check if a value is missing, and the 'coalesce()' function to replace missing values.

Describe the difference between Julia and Python.

While both Julia and Python are high-level programming languages used for scientific computing, they have some key differences. Julia is known for its speed and performance, which is comparable to languages like C and Fortran. Python is slower but is widely used due to its simplicity and the availability of libraries. Julia's syntax is more mathematical, making it more suitable for numerical and technical computing.

What are the main uses of Julia programming language?

Julia is primarily used for numerical and scientific computing. It is also used in data analysis and data science, machine learning, and in the development of large mathematical models.

How would you define Julia language?

Julia is a high-level, high-performance programming language for technical computing, with syntax that is familiar to users of other technical computing environments. It provides a sophisticated compiler, distributed parallel execution, numerical accuracy, and an extensive mathematical function library.

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

Is the candidate able to work well in a team and communicate effectively?

Soft skills are important in any role. Even if the candidate is technically proficient, they need to be able to work well with others and communicate their ideas clearly.

Does the candidate have experience with Julia's ecosystem, including its packages and tools?

Familiarity with the ecosystem can speed up development and improve the quality of the code. It also shows that the candidate is up-to-date with the Julia community.

Is the candidate able to optimize Julia code for performance?

Performance optimization is important in many applications of Julia, such as data science and machine learning. This skill can greatly benefit the team.

How well does the candidate understand and apply Julia's unique features, such as multiple dispatch and metaprogramming?

These features are part of what makes Julia powerful and efficient. A good understanding of them indicates a high level of proficiency.

Can the candidate effectively solve problems using Julia?

Problem-solving skills are key in any programming role. If they can demonstrate this ability, it shows they can use Julia to create effective solutions.

Does the candidate have a solid understanding of Julia's syntax and semantics?

This is crucial as it forms the basis of any programming task they will undertake. If they struggle with the basics, they may not be able to effectively contribute to the team.

Next 20 minutes

Specific Julia 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 multithreading in Julia?

Multithreading in Julia can be achieved using the '@threads' macro in combination with a 'for' loop. The '@threads' macro applies the loop iterations across the available computing cores, thus implementing multithreading.

What are the benefits of using Julia for data analysis?

Julia has a number of benefits for data analysis. It has a simple, high-level syntax that is easy to read and write. It is also high-performance, meaning it can handle large datasets and complex computations efficiently. Furthermore, it has strong support for parallel and distributed computing, and a large number of libraries for data manipulation and analysis.

How would you perform error handling in Julia?

Error handling in Julia is done using the 'try', 'catch', and 'finally' keywords. The 'try' block contains the code that may potentially throw an error, the 'catch' block contains the code to handle the error, and the 'finally' block contains code that will be executed regardless of whether an error was thrown or not.

Describe the difference between a Tuple and an Array in Julia.

In Julia, a Tuple is an ordered sequence of elements. It is immutable, meaning its elements cannot be changed once created. An Array, on the other hand, is a mutable data structure that can hold multiple items of the same type. Unlike Tuples, Arrays can be resized and their elements can be changed.

How would you define and call a function in Julia?

Functions in Julia are defined using the 'function' keyword followed by the function name, parentheses enclosing any arguments, and the function body, ending with 'end'. Functions are called by writing the function name followed by parentheses enclosing any arguments.

The hiring guide has been successfully sent to your email address.
Oops! Something went wrong while submitting the form.

The ideal back-end app developer

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

At this point in the interview, a skilled Julia engineer should demonstrate proficiency in Julia syntax and libraries, understanding of data analysis or machine learning algorithms using Julia, and problem-solving skills. Red flags include lack of knowledge in core concepts, inability to solve basic problems, or poor communication skills.

Digging deeper

Code questions

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

What does the following Julia code do?

println("Hello, World!")

This code prints the string 'Hello, World!' to the console.

What will be the output of the following Julia code?

x = 10
y = 20
println(x + y)

The output of the code will be 30. The code first assigns the values 10 and 20 to the variables x and y respectively, then it prints the sum of x and y.

What does the following Julia code do?

arr = [1, 2, 3, 4, 5]
println(sum(arr))

This code calculates the sum of all elements in the array 'arr' and prints the result, which is 15.

What does the following Julia code do?

@threads for i in 1:10
    println(i)
end

This code prints the numbers 1 through 10 in parallel using multiple threads. The order of the printed numbers may vary because the threads may not finish in the order they were started.

What does the following Julia code do?

struct Point
    x::Int
    y::Int
end

p = Point(1, 2)
println(p.x)

This code defines a type 'Point' with two fields 'x' and 'y'. It then creates an instance of 'Point' with 'x' as 1 and 'y' as 2. Finally, it prints the value of 'x' from the created 'Point' instance, which is 1.

What will be the output of the following Julia code?

function fib(n)
    n <= 2 ? 1 : fib(n - 1) + fib(n - 2)
end

println(fib(6))

The output of the code will be 8. The code defines a recursive function to calculate the nth Fibonacci number and then prints the 6th Fibonacci number.

Wrap-up questions

Final candidate for Julia role questions

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

What are metaprogramming capabilities in Julia and how would you use them?

Metaprogramming in Julia refers to the ability of the language to treat code as data and manipulate it. Julia provides several metaprogramming features, such as macros and symbolic computation. These can be used to generate and transform code programmatically, enabling more advanced programming techniques and improving performance.

Describe the difference between compiled and interpreted languages and where does Julia fall?

Compiled languages are converted into machine code before they are run, which can make them faster and more efficient. Interpreted languages, on the other hand, are converted into machine code as they are run, which can make them slower but more flexible. Julia uses a Just-In-Time (JIT) compiler, which compiles the code as it runs. This gives it the flexibility of an interpreted language and the speed of a compiled language.

How would you handle exceptions in Julia?

Exceptions in Julia are handled using a 'try-catch' block. The 'try' block contains the code that may throw an exception, and the 'catch' block contains the code to execute if an exception is thrown. The type of the exception can be specified to catch specific exceptions.

What are some ways to improve performance in Julia?

Performance in Julia can be improved in several ways. One is by avoiding global variables, which are slower than local variables. Another is by using type declarations, which allow the compiler to generate more efficient code. Using built-in functions and libraries, which are often optimized for performance, can also help.

Describe the difference between global and local scope in Julia.

In Julia, variables have either a global or local scope. Variables defined outside of any function or loop have a global scope and can be accessed from anywhere in the code. Variables defined inside a function or loop have a local scope and can only be accessed within that function or loop.

The hiring guide has been successfully sent to your email address.
Oops! Something went wrong while submitting the form.

Julia application related

Product Perfect's Julia development capabilities

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