Any class parameter is implicitly a class field

Any class parameter is implicitly a class field in Scala:

package ky.example

object Example {

  class A(elem: Int)
  class B(val elem: Int)
  class C(var elem: Int)

}


object Test {
  import Example._
  val a = new A(3)
  val b = new B(3)
  val c = new C(3)
  a.elem // error: cannot resolve symbol elem
  b.elem = 4 // error: reassignment to val
  c.elem = 4 // good
}

Note the difference between using val or var and not using any keyword at all.