Feedback Requested - HyperView State

[seanhess]

I added optional view state to HyperViews. I'd appreciate some feedback from anyone interested.

ViewState is entirely backwards-compatible: the default is ()

import Effectful.State.Static.Local

data Counter = Counter
  deriving (Generic)
instance ViewId Counter where
  type ViewState Counter = Int

instance HyperView Counter es where
  data Action Counter
    = Increment
    | Decrement
    deriving (Generic, ViewAction)

  update Increment = do
    modify @Int (+ 1)
    pure viewCount
  update Decrement = do
    modify @Int (subtract 1)
    pure viewCount

viewCount :: View Counter ()
viewCount = row $ do
  n <- viewState
  col ~ gap 10 $ do
    el ~ dataFeature $ text $ pack $ show n
    row ~ gap 10 $ do
      button Decrement "Decrement" ~ Style.btn
      button Increment "Increment" ~ Style.btn

In the name of simplicity, I've resisted implementing this for a long time. We aren't trying to implement the Elm Achitecture. Instead we have a simpler model that follows the design philosophy of htmx: actions call the server and replace the view with something. However, I don't think it will hurt to have it as an option.

Some outstanding limitations:

• modify, get, put, etc are from Effectful.State.Static.Local - It would be useful to export them from somewhere, but they might conflict with other State functions, like Effectful.State.Dynamic. They also require type annotations. Should we have specialized versions?
• For Technical Reasons (tm) I added it to ViewId instead of HyperView directly. (It makes working with dumb Views a pain in the ass if they all have to be members of HyperView).

[adithyaov]

I can take a look during the weekend if you'd like.