Thanks for the detailed breakdown on Pathom and cljfx subscriptions - this is exactly the kind of perspective I was hoping to hear.
The resolver model you describe (dumb functions, map-in → map-out, parallelizable) is appealing. It's similar to what I find elegant about React's model too - components as pure functions of props/state. The difference is where the "smarts" live: in the dependency graph engine vs in the reconciliation/diffing layer.
Your point about the 95% case resonates with vui.el's approach. We do have vui-use-memo for explicit memoization — so expensive computations can be cached with declared dependencies. It's the middle ground: you opt-in to memoization where it matters, rather than having an engine track everything automatically.
For typical Emacs UIs (settings panels, todo lists, file browsers), re-rendering the component tree on state change is fast enough that you rarely need it. But when you do — large derived data, expensive transformations — vui-use-memo is there. The tradeoff is explicit deps vs automatic tracking: you tell it what to cache and when to invalidate, rather than the framework inferring it.
That said, I'm planning to build a more complex UI for https://github.com/d12frosted/vulpea (my note-taking library) - browsing/filtering/viewing notes with potentially large datasets. That'll be a real test of whether my performance claims hold up against reality. So ff vui.el ever needs to go there, the component model doesn't preclude adding finer-grained updates later. The should-update hook already lets you short-circuit re-renders, and memoization could be added at the vnode level.
The caching/invalidation complexity you mention is what made me hesitant to start there. "Explicit deps are easier to trace than magic" was the tradeoff I consciously made. But I'm genuinely curious - if you do experiment with Pathom-backed GUI, I'd love to hear how it goes. Especially around the cache invalidation edge cases you mentioned.
I wrote my last message and then thought "oh gosh, it's so long, no one will read it". But I'm glad to find someone thinking about similar problems :))
> It's the middle ground: you opt-in to memoization where it matters, rather than having an engine track everything automatically.
What is the downside of just memoizing everything?
> you tell it what to cache and when to invalidate
I'd be curious to here more on this. I think the conceptual problem I'm hitting is more that these derived state systems (and this goes for a Pathom engine or a subscription model) seem to work optimally on "shallow" derived states. Ex: You have a "username" you fetch his avatar (one derived state) and then render it (maybe another derived state). That's fine.
But if now have a list of users... each has usernames and derived avatars and rendered images.. the list of users is changing with people being added and removed - this get mess.
With Pathom you can make username,avatar,render revolvers for the derived states. It's nicely decoupled and you can even put it in a separate library. With cljfx subscribers you can make subscriptions based on the state + username. It's more coupled, but you nolonger need an engine. Functionally it's the same.
But when it comes to the cache, I don't actually know any system that would handle this "correctly" - clearing cache entries when users are removed. Under the current solutions you seem to only have two solutions:
- You just sort of guess and make a "large enough" FIFO cache. You either eat memory or thrash the cache.
- Make Resolvers/Subscriptions on whole lists. So now you have usernames->avatars->renderings. This makes the derived states "shallow" again. If any entry is changed, the whole lists of derived states are recalculated. Memory optimal and fast to fetch (don't need to look check the memoization cache a ton). But if your list is rapidly changing, then you're doing a ton of recalculation.
I actually haven't worked with React directly, so I'd be curious to know how they propose dealing with this.
> if you do experiment with Pathom-backed GUI, I'd love to hear how it goes
The resolver model you describe (dumb functions, map-in → map-out, parallelizable) is appealing. It's similar to what I find elegant about React's model too - components as pure functions of props/state. The difference is where the "smarts" live: in the dependency graph engine vs in the reconciliation/diffing layer.
Your point about the 95% case resonates with vui.el's approach. We do have vui-use-memo for explicit memoization — so expensive computations can be cached with declared dependencies. It's the middle ground: you opt-in to memoization where it matters, rather than having an engine track everything automatically.
For typical Emacs UIs (settings panels, todo lists, file browsers), re-rendering the component tree on state change is fast enough that you rarely need it. But when you do — large derived data, expensive transformations — vui-use-memo is there. The tradeoff is explicit deps vs automatic tracking: you tell it what to cache and when to invalidate, rather than the framework inferring it.
That said, I'm planning to build a more complex UI for https://github.com/d12frosted/vulpea (my note-taking library) - browsing/filtering/viewing notes with potentially large datasets. That'll be a real test of whether my performance claims hold up against reality. So ff vui.el ever needs to go there, the component model doesn't preclude adding finer-grained updates later. The should-update hook already lets you short-circuit re-renders, and memoization could be added at the vnode level.
The caching/invalidation complexity you mention is what made me hesitant to start there. "Explicit deps are easier to trace than magic" was the tradeoff I consciously made. But I'm genuinely curious - if you do experiment with Pathom-backed GUI, I'd love to hear how it goes. Especially around the cache invalidation edge cases you mentioned.