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Elm# is a functional programming language for developing web applications. It was created by Evan Czaplicki in 2012 and is based on Haskell. Elm# is statically typed, which means that errors are caught at compile time, and it is also strongly typed, which means that values cannot be assigned to variables of the wrong type. Elm# is designed to be a safe language, and it has a number of features that help to prevent errors, such as type inference and pattern matching.

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

First 20 minutes

General Elm# app knowledge and experience

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

What are the key features of Elm#?

Elm# has several key features such as static typing, pure functions, immutable data, and a robust type inference system. It also has a built-in architecture pattern known as The Elm Architecture (TEA), and a reactive programming model.

How would you install Elm# in your development environment?

Elm# can be installed using npm (Node Package Manager). The command 'npm install -g elm' is used to install Elm globally on your machine.

What is the Elm Architecture?

The Elm Architecture (TEA) is a simple pattern for architecting web applications. It is built into Elm# and consists of three parts: Model, Update, and View.

How would you handle side effects in Elm#?

In Elm#, side effects such as HTTP requests are handled using Commands. Functions can return a Command along with the new model state, which describes some action for the Elm runtime to perform.

What are pure functions in Elm#?

Pure functions in Elm# are functions that always produce the same output given the same input and do not have any side effects.

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What you’re looking for early on

Does the candidate have a solid understanding of Elm# language?

How well does the candidate understand functional programming?

Can the potential hire solve problems effectively?

How good is the candidate's communication skills?

Next 20 minutes

Specific Elm# 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.

What is the difference between 'let' and 'in' keywords in Elm#?

'let' and 'in' keywords in Elm# are used for defining local variables. 'let' is used to start the definition and 'in' is used to end it.

How would you debug an Elm# application?

Elm# provides a time-traveling debugger, which allows you to move back and forth through the history of your program's state. It can be enabled by using the '--debug' flag when starting the Elm Reactor.

What is the difference between 'type' and 'type alias' in Elm#?

'type' is used to create a new type with its own set of values, while 'type alias' is used to create a new name for an existing type.

How would you handle errors in Elm#?

In Elm#, errors are handled using the 'Result' type, which represents either a successful result or an error. This encourages explicit error handling and makes it impossible to ignore errors.

What are Elm# signals?

Signals in Elm# represent values that change over time. They are a core concept in Elm's reactive programming model.

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

What does the following Elm code do?
import Html exposing (text)
main =
  text "Hello, World!"
This code prints 'Hello, World!' to the screen.
What will be the output of the following Elm code?
import Html exposing (text)
import List

main =
  text (List.toString (List.reverse [1, 2, 3, 4, 5]))
This code will output the list [5,4,3,2,1]. It reverses the list [1,2,3,4,5] and then converts it to a string for display.
What does the following Elm code do?
import Html exposing (text)
import List

main =
  text (List.toString (List.filter ((>) 3) [1, 2, 3, 4, 5]))
This code will output the list [4,5]. It filters the list [1,2,3,4,5] to only include numbers greater than 3, and then converts it to a string for display.
What does the following Elm code do?
import Html exposing (text)
import Task
import Time

main =
  Task.perform Time.second (always (text "Hello, World!"))
This code will print 'Hello, World!' to the screen after a delay of one second.

Wrap-up questions

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

What is the difference between 'map' and 'andThen' functions in Elm#?

'map' is used to apply a function to the successful result of a 'Result' or 'Maybe', while 'andThen' is used to chain together computations that might fail.

How would you optimize an Elm# application for performance?

Elm# applications can be optimized for performance by using techniques such as lazy evaluation, memoization, and using the '--optimize' flag when compiling.

What are Elm# ports?

Ports in Elm# are used for communication between Elm and JavaScript. They allow you to send and receive messages from JavaScript code.

Elm# application related

Product Perfect's Elm# development capabilities

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

Elm# Consultive assessments

Elm# Application Conversion Assessment Elm# Application Integration Assessment Elm# Data & Database Integration Assessment

Custom Elm# development projects

Custom Elm# App Conversion Elm# Custom App Development Process App UI Design for Elm# Facelifts

Hiring guide for Elm# Engineers

Elm# Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

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

Elm# Consultive assessments

Custom Elm# development projects