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Comment by dougk16 | Hacker News Reader

Just watched it...really great stuff. But can anyone chime in on how you can apply some of the principles in his talk to something like a retain-mode display library, for GUI or 3d for example? Libraries like these pop up in all popular OO languages and usually have long inheritance chains with very state-heavy classes, which further form somewhat rigid hierarchies of class instances at runtime. This violates some of his tenants in a big way, but they seem to be the predominant design pattern for getting stuff on screen. Even HTML5 is essentially like this.

Any thoughts on how his talk could apply here? Is there a better way?

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View layers can get complex, but you can at the very least encapsulate complexity and have it interact with other parts of the system in a simple well defined way. Have the separate layers of the application communicate via interfaces that keep the ingress, egress points of data flow well defined. Things like event pub/sub systems can further decouple things, the observer pattern, etc.

I meant that if I were designing a general-purpose retain-mode GUI library or 3d engine from the ground up and wanted to incorporate his principles as much as possible, how could I do that? Maybe a retain-mode approach is just inherently (too?) complex?

Correct me if I'm wrong, but I think your answer is in reference to using such a library, and I can certainly see how my question implied that, so sorry for the confusion if this is the case. Thanks for your answer regardless.

At that level it's similar tradeoffs. Consider what the code would look like if it were purely functional. In fact a good answer to your question would be for a thought exercise take a look at how XMonad is implemented in Haskell. That would be a completely different approach to the large, heavily coupled messes that OOP can sometimes lead to when modeling the state as mutable object members.

Thank you, I will look into that. Sorry, forgot to upvote you...fixed!

This is something I've been experimenting with. My intuition is that the scene graph will look a lot more like an AST made from algebraic data structures than an OOP actors network. Down that road, the system looks like an optimizing compiler with the really tricky added bit of iterating in response to user input.

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