Language Questions

• What is the difference between a var, a val and def?
• What is the difference between a trait and an abstract class?
• What is the difference between an object and a class?
• What is a case class?
• What is a companion object?
• What is the difference between the following terms and types in Scala: Nil, Null, None, Nothing?
• What is Unit?
• What is the difference between a call-by-value and call-by-name parameter?
  • How does Scala's Stream trait levarages call-by-name?
• Define uses for the Option monad and good practices it provides.
• How does yield work?
• Explain the implicit parameter precedence.
• What operations is a for comprehension syntactic sugar for?
• Streams:
  • What consideration you need to have when you use Scala's Streams?
  • What technique does the Scala's Streams use internally?

TODO

• What is the difference between Java future and Scala future?
• What is the difference between unapply and apply, when would you use them?