Difference between call by name and normal parameters in Scala.

gistfile1.scala

val counter = new java.util.concurrent.atomic.AtomicInteger(0)

def printTwiceExpression(expression: => Int) = {
  println(expression)
  println(expression)
}
def printTwiceValue(value:  Int) = {
  println(value)
  println(value)
}

printTwiceExpression(counter.incrementAndGet())
printTwiceValue(counter.incrementAndGet())