Editing POV-Ray SDL project (section)

== The idea ==

For many years now the authors of POV-Ray have been looking at implementing more powerful programming constructs in the SDL. Endless flamewars have raged over the subject of whether the SDL should become object-oriented.

What ''nobody'' wants is for the SDL to end up looking like this:

 new Camera(new Vector3(0, 0, -5), new Vector3(0, 0, 0));

 new LightSource(new Vector3(-2, +3, -5), Colour.White);

 Finish f = new Finish(0, 0.7, 0.5);
 Texture t = new Texture(Colour.Red, f);
 Object o1 = new Object(new Sphere(new Vector3(0, 0, 0), 2), t);

I have personally written a ray tracer in Java, and the above is ''exactly'' the kind of thing you end up writing to construct test scenes to render. Urgh! Never again!!

On the other hand, Haskell is a very simple, elegant and powerful programming language. To make matters even more tantalising, the existing SDL is already ''almost valid Haskell source code!'' All you have to do is write a big tedious thing like this:

<haskell>
module POVRay where

data Shape =
  Plane {normal :: Vector3, distance :: Real} |
  Sphere {center :: Vector3, radius :: Real} |
  ...

data Finish = Finish {ambient :: Colour, diffuse :: Colour, ... }

data Texture = Texture {pigment :: Colour, finish :: Finish, ... }
</haskell>

Once the above is imported, most valid SDL files suddenly become valid Haskell!