1 

     2 import scala.concurrent._

     3 import scala.concurrent.duration._

     4 import ExecutionContext.Implicits.global

     5 import scala.language.postfixOps 

     6 import scala.language.reflectiveCalls

     7 

     8 lazy val f = Future {

     9   import CW8a._

    10 

    11   assert(nullable(ZERO) == false)

    12   assert(nullable(ONE) == true)

    13   assert(nullable(CHAR('a')) == false)

    14   assert(nullable(ZERO | ONE) == true)

    15   assert(nullable(ZERO | CHAR('a')) == false)

    16   assert(nullable(ONE ~  ONE) == true)

    17   assert(nullable(ONE ~ CHAR('a')) == false)

    18   assert(nullable(STAR(ZERO)) == true)

    19 }

    20 

    21 Await.result(f, 120 second)