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Elixir Structs is a software library for the Elixir programming language that provides a rich set of data structures. It was created in 2014 by José Valim and is open-source software. Elixir Structs is used by a variety of companies, including Google, Amazon, and Microsoft.

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

First 20 minutes

General Elixir Structs app knowledge and experience

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

What are the main uses of Elixir Structs?

Elixir Structs are used for defining custom data types with predefined keys and default values. They are commonly used for encapsulating related data into a single entity, making the code more readable and maintainable.

How would you define a struct in Elixir?

In Elixir, a struct is defined using the defstruct keyword inside a module. For example, defmodule User do defstruct [:name, :email] end. This will define a User struct with fields name and email.

Describe the difference between Elixir Structs and Maps.

Structs are a special kind of Map that have a fixed set of fields with default values. Unlike Maps, they provide compile-time checks and can have functions associated with them.

How would you update a field in a struct?

You can update a field in a struct using the Map.put function or the struct update syntax. For example, user = %User{name: 'John'}; user = %{user | name: 'Jane'}.

What happens when you try to access a field that does not exist in a struct?

If you try to access a field that does not exist in a struct, Elixir will raise an error. This is one of the ways structs provide more safety compared to maps.

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What you’re looking for early on

Does the candidate showcase a strong understanding of Elixir Structs?

How well does the candidate understand the concepts of functional programming?

Can the candidate solve problems using Elixir?

Does the candidate demonstrate good communication skills?

Next 20 minutes

Specific Elixir Structs 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 define a function that operates on a struct?

You can define a function that operates on a struct by pattern matching on the struct in the function definition. For example, defmodule User do defstruct [:name]; def greet(%User{name: name}), do: IO.puts "Hello, #{name}" end.

What is the purpose of the __struct__ field in Elixir Structs?

The __struct__ field in an Elixir Struct holds the name of the struct's module. It is used by Elixir to identify the data as a struct of a particular type.

How would you convert a Map to a Struct?

You can convert a Map to a Struct using the struct function. For example, map = %{name: 'John', email: 'john@example.com'}; user = struct(User, map).

What are the benefits of using Structs over Maps in Elixir?

Structs provide compile-time checks and can have default values. They also allow you to define functions that operate on them, providing a way to encapsulate behavior with data.

How would you define a struct with default values for its fields?

You can define a struct with default values for its fields by providing a default value in the defstruct definition. For example, defmodule User do defstruct name: 'Anonymous', email: '' end.

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

What does this Elixir Struct code do?
defmodule User do
  defstruct name: "", age: 0
end
This code defines a struct called 'User' with two fields: 'name' and 'age'. The default value for 'name' is an empty string and for 'age' it is 0.
What will be the output of the following Elixir code?
defmodule User do
  defstruct name: "John", age: 30
end

IO.inspect %User{name: "Doe"}
The output will be a User struct with 'name' field set to 'Doe' and 'age' field set to default value 30. So, the output will be: %User{age: 30, name: "Doe"}.
What does this Elixir Structs code do?
defmodule User do
  defstruct [:name, :age]
end

users = [%User{name: "John"}, %User{age: 30}]
Enum.map(users, fn user -> user.age end)
This code defines a struct 'User' with fields 'name' and 'age'. Then it creates a list of 'User' structs and uses the 'Enum.map' function to create a new list that contains only the 'age' of each user. The result is a list of ages.
What does this Elixir Structs code do regarding concurrency?
defmodule User do
  defstruct [:name, :age]
end

user1 = %User{name: "John", age: 30}
user2 = %User{name: "Doe", age: 20}

spawn_link(fn -> IO.inspect(user1) end)
spawn_link(fn -> IO.inspect(user2) end)
The code creates two User structs and then spawns two separate processes that each print a User struct. The 'spawn_link' function is used for creating new processes in Elixir, demonstrating basic concurrency.

Wrap-up questions

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

What is the difference between the struct and the %{} syntax?

The struct function is used to create a new struct or update an existing one, while the %{} syntax is used to create a new struct. The struct function also allows you to convert a Map to a Struct.

How would you handle optional fields in a struct?

Optional fields in a struct can be handled by providing a default value in the struct definition. When creating a new struct, you can omit these fields and they will be set to their default values.

What happens if you try to create a struct with an unknown field?

If you try to create a struct with an unknown field, Elixir will raise a KeyError. This is because structs have a fixed set of fields defined at compile time.

Elixir Structs application related

Product Perfect's Elixir Structs development capabilities

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

Elixir Structs Consultive assessments

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

Custom Elixir Structs development projects

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

Hiring guide for Elixir Structs Engineers

Elixir Structs 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 Structs engineer at this point.

Elixir Structs Consultive assessments

Custom Elixir Structs development projects