Module Final

A convenience module to create a final version of a type, for the purposes of extending it in a parameterized module, without having to define a new final alias of that type.

module MyModule<...> {
  // Using this module:
  class MyExpr extends Final<Expr>::Type { ... }

  // Ordinary behavior:
  // Error: cannot extend types outside the current parameterized module
  class MyExpr extends Expr { ... }

  // Ordinary behavior:
  // Workaround: define a new final alias of the type
  class FinalExpr = Expr;
  class MyExpr extends FinalExpr { ... }
}