Perfect, thanks to you both. On Thu, Aug 20, 2015 at 1:50 PM, Michael Steele wrote:

Michael,

In case your interested in another example, there's also a quadtree in the "gloss-algorithms" [1] package.

[1]: http://hackage.haskell.org/package/gloss-algorithms

On Thu, Aug 20, 2015 at 1:41 PM, Tikhon Jelvis wrote:

...

Are you already familiar with lenses? From a glance at the code you linked, it will be hard to understand what's going on unless you are.

Personally, my advice is to implement a simple, limited quadtree yourself. The first part of "Functional Programming with QuadTrees"[1] is basically a tutorial on quadtrees with code in Miranda—eminently readable for Haskellers. That's where I would start: write up the code from their examples in Haskell, play around with it and add an extra function or two to understand what's going on.

Once you have an intuition for the underlying ideas, you can expand it to octtrees and more complex operations.

[1]: http://conal.net/papers/warren-burton/Functional%20Programming%20and%20Quadt...

On Thu, Aug 20, 2015 at 1:30 PM, Michael Litchard wrote:

...

It looks like Octree is what I want if I can solve a particular problem. First let me articulate what I am looking for.

(1) Objects in 3-d space with no spatial extent. Collision is determined by two objects occupying the same point.'

(2) Efficient insert-delete-update

#2 seems to be the problem. I found this library, thankfully. I believe it's exactly what I am looking for, but for quadtrees.

https://github.com/AshleyMoni/QuadTree

I'm a little overwhelmed as this is a new data structure for me. I believe if I can grok what is going on in this library, I can take these ideas and extend them to the octree. I'm referring specifically to this module

https://github.com/AshleyMoni/QuadTree/blob/master/Data/QuadTree/Internal.hs

And these functions

setLocation :: Eq a => Location -> a -> QuadTree a -> QuadTree a setLocation = set . atLocation

atLocation (Having difficulty cutting and pasting this to mail.)

I'd like to be able to visualize how the tree is being compressed, it may help to be able to see what happens to the tree when it's not compressed.

Does anyone have a pointer or advice in how to break this library down in parts to help me grok, in a way that will help me extend to octree?

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-- -- Michael Steele