Scala school questions

scala-school-questions.md

• Scala syntax

  • How well do you know Option/Try/Either/Future types from Scala standard library?
    • I don't use them
    • I use them, but I don't see clear benefits
    • I use them and understand the benefits, but I struggle with them
    • I fully understand why we use them and have no problems with them
  • How do you get and combine values from those types mentioned above?
    • I don't
    • I use map/flatMap most of the time
    • I try using for-comprehension most of the time
    • I fallback to match/case (arrow) pattern matching when it's getting more complicated
  • How often you use implicit parameters
    • Whatever those are...
    • I use them to change the way my functions are executing their logic
    • They only bring unclarity and can be dangerous, so I just pass values explicitly
    • I always mix them up with other implicits
  • Context bounds are something related to...
    • syntactic sugar for implicit parameter on specific type
    • something that is related to class inheritance
    • domain driven design, not Scala
  • I feel that immutable variables/collections are...
    • solving some problems with multithreading, but are bringing other problems
    • only the way functional programming works
    • only slowing me down, I would rather use mutable variables/collections
    • simplifying the reasoning and predictability of my applications as well as easier parallel processing
  • Which benefits do you see in lazy evaluation?
    • Pure functional programming would be impossible without it (ignoring the-end-of-the-world)
    • Except making code more complicated, not much
    • I use them sometimes for better performance and to pass functions as arguments
  • How often do you end up using Future[Either[Error, T]] in your application?
    • I'm not familiar with it
    • Why using Either when you can throw exceptions?
    • I want to use it most of the time, but getting values from them is tedious
    • I use something equivalent or better with the help of functional libraries
    • I use them together with monadic transformers
  • Do you use ADT in your applications?
    • Never
    • I've heard about it, but I'm not using them much
    • I use it whenever I can
  • Are you familiar with concept of higher-kinded types?
    • Not really
    • Yes, and I'm using it as much as possible to make my code more general
    • Yes, but I rarely have a need to think about it

• FP concepts

  • Do you use some libraries for functional programming (cats, scalaz)?
    • I use them in production
    • No, but I know about them from books or articles
    • I tried them on my own, but not on production code
    • Never heard about them
  • Do you know what pure function is?
    • I'm not really sure
    • Yes, and I write all my functions as pure functions
    • Yes, but I find hard accepting that concept in real applications
  • Do you think that Future[T] from standard library is referentially transparent?
    • Of course, it is
    • Nope
    • I don't know what is referential transparency
  • Are you using typeclasses in your daily business?
    • Yes!
    • I think I do
    • I've heard about them, but don't use them
  • Are you familiar with concepts of monoid, functor, applicative and monad and why do we have them?
    • No, I don't
    • They are too confusing for me
    • Yes and yes
    • Only in theory, didn't use them in practice
  • Does any of following terms ring a bell for you: monadic transformers, free monad, tagless final, IO monad
    • Yes, all of them
    • No, I'm not into those things
    • Yes, but not all of them

• General

  • How many tests usually fail when you refactor one function which is not used a lot in the project?
    • None
    • One or two
    • Many of them
  • When I'm designing my application, I create classes that...
    • are containing data and functions that are working with that data
    • are containing only data, functions for that data is defined elsewhere
    • are containing everything related to this entity
  • Which approach you take to test functionalities that are using external libraries (AWS SDK for example)?
    • I just mock all of them
    • I wrap everything related to them in separated classes and mock them
    • I dockerize the service or add a library in project that emulates that service
    • Something else

• Tooling, patterns and libs

  • play framework questions?
  • Which JSON library do you use most of the time?
    • Play JSON all the way down
    • Circe
    • Some Java library
    • Something else
  • Which mocking library do you use most of the time?
    • mockito
    • ScalaMock
    • Because of tagless final I never or rarely use it
  • Did you ever use shapeless library?
    • I'm not familiar with that library
    • Yes
    • I rarely find a reason for it

• Free text fields:

  • What are your biggest pain points when you're working with Scala?
  • What would you expect from a Scala school?