Xprintの例

x_print.scala

$ scalac -Xprint:typer Foo.scala
[[syntax trees at end of                     typer]] // Foo.scala
package <empty> {
  object Main extends AnyRef with App {
    def <init>(): Main.type = {
      Main.super.<init>();
      ()
    };
    def foo(x: Option[Int]): Unit = x match {
      case (x: Int)Some[Int]((a @ _)) => scala.this.Predef.println(a)
      case scala.None => scala.this.Predef.println("null")
    };
    Main.this.foo(scala.Some.apply[Int](3))
  }
}


$ scalac -Xprint:patmat Foo.scala
[[syntax trees at end of                    patmat]] // Foo.scala
package <empty> {
  object Main extends AnyRef with App {
    def <init>(): Main.type = {
      Main.super.<init>();
      ()
    };
    def foo(x: Option[Int]): Unit = {
      case <synthetic> val x1: Option[Int] = x;
      case6(){
        if (x1.isInstanceOf[Some[Int]])
          {
            <synthetic> val x2: Some[Int] = (x1.asInstanceOf[Some[Int]]: Some[Int]);
            {
              val a: Int = x2.x;
              matchEnd5(scala.this.Predef.println(a))
            }
          }
        else
          case7()
      };
      case7(){
        if (scala.None.==(x1))
          matchEnd5(scala.this.Predef.println("null"))
        else
          case8()
      };
      case8(){
        matchEnd5(throw new MatchError(x1))
      };
      matchEnd5(x: Unit){
        x
      }
    };
    Main.this.foo(scala.Some.apply[Int](3))
  }
}