Scala example source code file (tcpoly_typesub.scala)

This example Scala source code file (tcpoly_typesub.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

typesub, typesub

The Scala tcpoly_typesub.scala source code

// contributed by Lauri Alanko
trait TypeSub {
  type l
  type u
  def castSub[f[+x]](fl : f[l]) : f[u]
  def castSuper[f[-x]](fu : f[u]) : f[l] = {
    type c[+y] = f[y] => f[l]
    castSub[c]{ fl : f[l] => fl }(fu)
  }
  def castValue[t](lt : l with t) : u with t = {
    type c[+y] = y with t
    castSub[c](lt)
  }
}