[Haskell-cafe] Profiling nested case

[Justin Bailey]

2008/7/9 Mitar <mmitar at gmail.com>:

>
> And it took 15 s. And also the profiling was like I would anticipate.
> Calculating points coordinates and checking spheres takes almost all
> time.
>
> So any suggestions how could I build a list of objects to check at
> runtime and still have this third performance? Why this big
> difference?

I think the speed difference really comes from using a list to hold
the spheres in your first two examples, to referring to them directly
in case statements in your last example. Lists are going to introduce
indirections and therefore are slower than referring directly to the
values themselves.

Maybe you would have better luck using arrays? Template Haskell is
also an option - if you want to "hard code" your scene in another
module, TH can turn it into that kind of case statement. Of course, as
the scenes get more complex a series of nested cases isn't going to be
too effecient.

Justin