[Haskell-cafe] Loops and ray casting with GPipe?

Greetings, With OpenGL shaders it is possible to write code utilizing loops with unknown number of iterations, I'm wondering if the same can be done with GPipe? Fractals would be one use case and implicit surfaces another. Fragment Floats had to be compared with IfB from Data.Boolean, so I tried something recursive like foo x = boolean x (foo (x * 0.9)) (x <* 1) which compiles fine but seems to concentrate on eating stack space while running :)