Product Perfect

Elixir Mix is a dynamic, functional programming language designed for building scalable and maintainable applications. It was created by José Valim in 2011, as an extension of the Erlang Virtual Machine (BEAM), aiming to enable higher extensibility and productivity. Elixir Mix supports metaprogramming allowing macro definitions for code generation and manipulation. Its concurrency model, built on Actor Model principles, enables it to handle many lightweight processes simultaneously with high fault tolerance. As a part of the Elixir language ecosystem, it provides tasks mix tooling that manages project dependencies and executes tests.

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

First 20 minutes

General Elixir Mix app knowledge and experience

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

What is the purpose of Mix in Elixir?

Mix is a build tool that provides tasks for creating, compiling, and testing Elixir projects, managing its dependencies, and more.

How would you create a new Elixir project using Mix?

You can create a new Elixir project by running 'mix new project_name' in the command line. This will create a new directory with the necessary files and directory structure for an Elixir project.

What are Mix tasks?

Mix tasks are scripts that can be run from the command line. They are used to automate common tasks such as compiling code, running tests, generating documentation, etc.

How would you run tests in an Elixir project using Mix?

You can run tests in an Elixir project by running 'mix test' in the command line. This will run all test files in the 'test' directory.

What is the purpose of the mix.exs file in an Elixir project?

The mix.exs file is the main configuration file for a Mix project. It contains information about the project and its dependencies, and defines tasks that can be run with the 'mix' command.

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What you’re looking for early on

Does the candidate have a solid understanding of Elixir Mix?

Can the candidate demonstrate experience with concurrent programming?

Has the candidate shown an ability to solve problems using Elixir Mix?

Does the candidate have experience with other Elixir tools and libraries?

Next 20 minutes

Specific Elixir Mix 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 add a dependency to an Elixir project using Mix?

You can add a dependency to an Elixir project by adding it to the deps function in the mix.exs file, and then running 'mix deps.get' in the command line to fetch and compile the dependency.

What is the difference between 'mix compile' and 'mix run'?

'mix compile' compiles the source files in your project, while 'mix run' compiles and then runs the application.

How would you generate documentation for an Elixir project using Mix?

You can generate documentation for an Elixir project by running 'mix docs' in the command line. This requires the ExDoc package to be added as a dependency in the mix.exs file.

What are the steps to publish a package in Hex using Mix?

To publish a package in Hex using Mix, you need to register an account on Hex, add :hex as a dependency in your mix.exs file, run 'mix hex.publish' in the command line, and follow the prompts.

How would you handle different environments in an Elixir project using Mix?

You can handle different environments in an Elixir project by using Mix.env. This returns the current environment, which can be set with the MIX_ENV environment variable.

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At this point, a skilled Elixir Mix engineer should demonstrate strong problem-solving abilities, proficiency in Elixir Mix 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 Elixir Mix.

What does this simple Elixir code do?
IO.puts "Hello, World!"
This code prints the string 'Hello, World!' to the console.
What will be the output of this Elixir code?
list = [1, 2, 3, 4]
Enum.reduce(list, 0, &+/2)
This code sums up all the elements in the list. The output will be 10.
What does this Elixir code do?
list = [1, 2, 3, 4, 5]
Enum.map(list, fn x -> x * 2 end)
This code takes a list of integers and returns a new list where each element is multiplied by 2.
What does this Elixir code do?
spawn(fn -> 1 + 2 end)
This code creates a new process that executes the function, which adds 1 and 2. However, the result is not used or returned anywhere.

Wrap-up questions

Final candidate for Elixir Mix 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 Elixir Mix application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

What is the purpose of the 'mix deps' command?

The 'mix deps' command is used to manage the dependencies of a Mix project. It can be used to fetch, compile, and list the dependencies.

How would you create a custom Mix task?

You can create a custom Mix task by defining a new module with a function named 'run' that takes a list of command-line arguments. The module should use the Mix.Task behaviour and be named with the pattern Mix.Tasks.TaskName.

What is the difference between 'mix deps.get' and 'mix deps.compile'?

'mix deps.get' fetches the dependencies and 'mix deps.compile' compiles them. 'mix deps.get' needs to be run before 'mix deps.compile'.

Elixir Mix application related

Product Perfect's Elixir Mix development capabilities

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

Elixir Mix Consultive assessments

Elixir Mix Application Conversion Assessment Elixir Mix Application Integration Assessment Elixir Mix Data & Database Integration Assessment

Custom Elixir Mix development projects

Custom Elixir Mix App Conversion Elixir Mix Custom App Development Process App UI Design for Elixir Mix Facelifts

Hiring guide for Elixir Mix Engineers

Elixir Mix Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

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

Elixir Mix Consultive assessments

Custom Elixir Mix development projects