[xymus]

I'm a developer on the Nit project, I would like to clarify a few points.

Classes and types are definitely static in Nit. Class refinement is applied at compilation and any ambiguity is reported at that time.

After using this language for a few years, I'm now convinced that class refinement is an improvement to manage preoccupations in projects of any size. It adds an additional layer to the classic object oriented languages. Nit uses classes to encapsulated data only, and modules to separate preoccupations. It saves us from using services classes and instead we can organize our methods in the real receiver of each behavior.

Let's take the example of a game. In module `game_logic`, we define the `Game` class with all the required methods and attributes for the full logic. In another module `graphics`, we reopen `Game` to add the `draw` method and the attributes to store the images. We end up with two modules, one that is simple to read and easy to test, and the other with only graphical preoccupations. We can even use class refinement to apply optimization without complicating the base game logic.

See the Hunted Dino project for an example of such a structure: https://github.com/privat/nit/tree/master/examples/mnit_dino...