Hiring guide for Frege Engineers

Frege Developer Hiring Guide

Frege is a non-strict, strongly-typed, functional programming language that is a Haskell for the Java Virtual Machine (JVM). Named after Gottlob Frege, a significant figure in the field of logic and mathematics, this language was developed to bring purely functional programing to the JVM. It closely follows the Haskell2010 standard and even shares its syntax and semantics. The Frege compiler translates Frege programs into Java, allowing seamless integration with any existing Java libraries. This unique feature makes it an attractive choice for developers seeking to leverage the robustness of JVM while enjoying the benefits of functional programming.

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

First 20 minutes

General Frege app knowledge and experience

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

How would you describe Frege's type inference?
Frege's type inference is strongly static, similar to Haskell. It uses the Hindley-Milner type system to infer the types of expressions without explicit type annotations.
What are the basic data types in Frege?
Frege has several basic data types including Int, Double, Char, and Bool, among others. It also supports complex data types like lists, tuples, and user-defined types.
Describe the difference between Lazy and Strict evaluation in Frege.
Lazy evaluation means that expressions are not evaluated until their results are needed. Strict evaluation means that expressions are evaluated as soon as they are bound to a variable. Frege uses strict evaluation by default but can also support lazy evaluation when needed.
How would you define a function in Frege?
In Frege, you define a function using the 'fun' keyword followed by the function name, parameters, and the equals sign, and then you write the function body. The return type of the function is inferred by the compiler.
What are Algebraic Data Types in Frege?
Algebraic Data Types (ADTs) in Frege are a way of creating new data types. They can be either product types (data types with multiple parts) or sum types (data types that can be one of many possible variants).
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What you’re looking for early on

Does the candidate possess a sound understanding of Frege's syntax and semantics?
Has the candidate demonstrated problem-solving abilities?
Can the candidate effectively work with Frege's type system?
Does the candidate have experience with functional programming paradigms?

Next 20 minutes

Specific Frege 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 handle exceptions in Frege?
Frege has a 'try' expression for handling exceptions. It allows you to catch and handle exceptions in a controlled manner.
What are type classes in Frege, and how would you use them?
Type classes in Frege provide a way to define behavior that can be shared across multiple types. You can define a type class with the 'class' keyword, and then define functions that work on any type that is an instance of that class.
Describe the difference between 'let' and 'where' in Frege.
'Let' and 'where' are both used to define local bindings in Frege, but they differ in their scope. 'Let' bindings are expressions that can be used anywhere, while 'where' bindings are only visible to the function they are defined in.
How would you use pattern matching in Frege?
Pattern matching in Frege is used to check the structure of data and extract values from it. It's done using the 'case' keyword, followed by the expression to match, and a series of patterns and corresponding results.
What are Monads in Frege, and how would you use them?
Monads in Frege are a way of handling side effects in a functional programming language. They encapsulate computations with side effects in a way that allows them to be composed and sequenced in a pure, functional manner.
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The ideal back-end app developer

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

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

What does the following simple Frege code do?
main _ = println 'Hello, World!'
This code prints the string 'Hello, World!' to the console.
What does the following Frege code do?
add x y = x + y
main args = println (add 5 6)
This code defines a function 'add' that adds two numbers together. It then calls this function with the arguments 5 and 6, and prints the result to the console.
What does the following Frege code do?
main args = println (map (*2) [1,2,3,4,5])
This code maps the function (*2) over the list [1,2,3,4,5], effectively doubling each element in the list. The result is printed to the console.
What does the following Frege code do?
main args = do
  forkIO (println 'Hello from a thread!')
  println 'Hello from the main thread!'
This code creates a new thread that prints 'Hello from a thread!' to the console. It then prints 'Hello from the main thread!' from the main thread.

Wrap-up questions

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

Describe the difference between 'pure' and 'impure' functions in Frege.
Pure functions in Frege are functions that do not have any side effects. They always produce the same output for the same input. Impure functions, on the other hand, can have side effects and their output can vary for the same input.
How would you create and use a custom type class in Frege?
You can create a custom type class in Frege using the 'class' keyword, followed by the name of the class and its type variable. You can then declare any functions that should be part of this class. To use this class, you declare a type as an instance of the class and implement the required functions.
What are Higher-Order Functions in Frege?
Higher-Order Functions in Frege are functions that can take other functions as arguments or return functions as results. They are a key feature of functional programming and are used extensively in Frege.

Frege application related

Product Perfect's Frege development capabilities

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