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

for method that dont have a return value, a way to express such methods is leaving out the result type and the equals sign, following the method with a block enclosed in curly braces. In this form, the method looks like a procedure, a method that is executed only for its side effects.