Scala example source code file (test5.scala)

This example Scala source code file (test5.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

f, g, g, i, j, m, m, n, p, p, unit, x, x, y

The Scala test5.scala source code

import scala._;

object test {

  trait F[If] {}

  def f[Jf](h: Jf):F[Jf] = f[Jf](h);

  trait G[Ig] {}

  def g[Jg](h: Jg):G[Jg] = g[Jg](h);

  class M[P]() {
      abstract class I[X]() {
	  // Methods to check the type X and P as seen from instances of I
	  def chk_ix(x: X): Unit = ();
	  def chk_ip(p: P): Unit;

	  // Value with type X as seen from instances of I
	  def val_ix: X = val_ix;
      }

      val i:I[G[P]] = null;

      // Values with types P and i.X as seen from instances of M
      def val_mp: P = val_mp;
      def val_mix: G[P] = g[P](val_mp);
  }

  class N[Q]() extends M[F[Q]]() {
      val j:J[G[Q]] = null;

      abstract class J[Y]() extends I[G[Y]]() {
	  // Values with types Y and X as seen from instances of J
	  def val_jy: Y = val_jy;
	  def val_jx: G[Y] = g[Y](val_jy);

	  // Check type P
	  chk_ip(val_mp);
	  chk_ip(val_np);
      }

      // Values with types Q, X.P, i.X, j.Y and j.X as seen from instances of N
      def val_nq: Q = val_nq;
      def val_np: F[Q] = f[Q](val_nq);
      def val_nix: G[F[Q]] = g[F[Q]](val_np);
      def val_njy: G[Q] = g[Q](val_nq);
      def val_njx: G[G[Q]] = g[G[Q]](val_njy);

      // Check type i.P
      i.chk_ip(val_mp);
      i.chk_ip(val_np);

      // Check type j.P
      j.chk_ip(val_mp);
      j.chk_ip(val_np); 

      // Check type i.X
      i.chk_ix(i.val_ix);
      i.chk_ix(val_mix);
      i.chk_ix(val_nix);

      // Check j.X
      j.chk_ix(j.val_ix);
      j.chk_ix(j.val_jx);
      j.chk_ix(val_njx); 
  }
}