blob: 36d6fc9530b1511b5410a672f99fa5f7d1c81a1f (
plain) (
tree)
|
|
abstract class Term[T];
case class Lit(x: int) extends Term[int];
case class Succ(t: Term[int]) extends Term[int];
case class IsZero(t: Term[int]) extends Term[boolean];
case class If[T](c: Term[boolean],
t1: Term[T],
t2: Term[T]) extends Term[T];
object Test extends Application {
def eval[T](t: Term[T]): T = t match {
case Lit(n) => n
case Succ(u) => eval(u) + 1
case IsZero(u) => eval(u) == 0
case If(c, u1, u2) => eval(if (eval(c)) u1 else u2)
}
Console.println(
eval(If(IsZero(Lit(1)), Lit(41), Succ(Lit(41)))))
}
|