When to use the equals sign in a Scala method declaration?

Question

With equals sign:

object HelloWorld {
  def main(args: Array[String]) = {
    println(\"Hello!\")
  }
}

Without equals sign:

Answer 1

You must use equals sign in call declarations except the definitions returning Unit.

In this latter case, you may forgo the equals sign. This syntax may be deprecated, though, so it's best avoided. Using equals sign and declaring the return type will always work.