Hard time understanding the basics of Scala-CodePudding

I'm a seasoned Python developer and I have to learn Scala for my new job. I had a great time practicing Python with CodeWars and decided to try with Scala as well, but there's just something that I can't understand...

Bellow I have a partial solution to an exercise, you can find it here https://www.codewars.com/kata/5c8bfa44b9d1192e1ebd3d15/train/scala

object SheepAdvisor {
  
  def warnTheSheepCheck(queue: Array[String]): String =
    // println(queue)
    if (queue.last == "wolf") {
      "Pls go away and stop eating my sheep"
    } else {
      s"Oi! Sheep! You are about to be eaten by a wolf!"
    }
}

What I don't understand is, why can't I just print the input? If I uncomment the print statement the entire code breaks. It just doesn't make sense to me.

The error:

src/main/scala/solution.scala:4: error: type mismatch;
 found   : Unit
 required: String
    println(queue)
           ^
src/main/scala/solution.scala:5: error: not found: value queue
    if (queue.last == "wolf") {

I'm really used to just attack a problem by small parts, usually printing stuff to verify that I'm on the right track. Is it some sort of paradigm shift with Scala that I just don't know about?

Any Scala resources focused on people coming from Python would be very much appreciated!

CodePudding user response：

For Scala 2 (available on Codewars) you need to wrap the whole function body in curly brackets otherwise compiler treats warnTheSheepCheck as invocation of println which returns Unit:

object SheepAdvisor {
  def warnTheSheepCheck(queue: Array[String]): String = {  // here
    println(queue)
    if (queue.last == "wolf") {
      "Pls go away and stop eating my sheep"
    } else {
      s"Oi! Sheep! You are about to be eaten by a wolf!"
    }
  }  // and here
}

Scala 3 has optional braces feature which allows to omit braces in this case.