Created
November 29, 2021 21:42
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trying to figure out type signature of render and handleAction to work with halogen store
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| module Main where | |
| import Prelude | |
| import Effect (Effect) | |
| import Effect.Aff (launchAff_) | |
| import Halogen.Aff as HA | |
| import Halogen.Store.Monad (runStoreT) | |
| import Halogen.VDom.Driver (runUI) | |
| import Data.Maybe (Maybe(..)) | |
| import Halogen as H | |
| import Halogen.HTML as HH | |
| import Halogen.HTML.Events as HE | |
| import Halogen.Store.Connect (Connected, connect) | |
| import Halogen.Store.Monad as Store | |
| import Halogen.Store.Monad (runStoreT, class MonadStore, StoreT) | |
| import Halogen.Store.Select (Selector, selectEq) | |
| import Effect.Aff (Aff) | |
| import Data.Const (Const) | |
| main :: Effect Unit | |
| main = launchAff_ do | |
| body <- HA.awaitBody | |
| root <- runStoreT initialStore reduce component | |
| runUI root unit body | |
| type Store = { count :: Int } | |
| initialStore :: Store | |
| initialStore = { count: 0 } | |
| data StoreAction | |
| = StoreIncrement | |
| | StoreDecrement | |
| reduce :: Store -> StoreAction -> Store | |
| reduce store = case _ of | |
| StoreIncrement -> store { count = store.count + 1 } | |
| StoreDecrement -> store { count = store.count - 1 } | |
| type Input = Unit | |
| type Context = Int | |
| type State = Int | |
| data Action | |
| = Increment | |
| | Decrement | |
| | Receive (Connected Context Input) | |
| deriveState :: Connected Context Input -> State | |
| deriveState { context } = context | |
| selectCount :: Selector Store Context | |
| selectCount = selectEq _.count | |
| component :: H.Component (Const Unit) Input Void (StoreT StoreAction Store Aff) | |
| component = connect selectCount $ H.mkComponent | |
| { initialState: deriveState | |
| , render | |
| , eval: H.mkEval $ H.defaultEval | |
| { handleAction = handleAction | |
| , receive = Just <<< Receive | |
| } | |
| } | |
| -- Trying to figure out what this type signature should be | |
| render :: _ | |
| render count = | |
| HH.div_ | |
| [ HH.button | |
| [ HE.onClick \_ -> Increment ] | |
| [ HH.text "Increment" ] | |
| , HH.text $ " Count: " <> show count <> " " | |
| , HH.button | |
| [ HE.onClick \_ -> Decrement ] | |
| [ HH.text "Decrement" ] | |
| ] | |
| -- Trying to figure out what this type signature should be | |
| handleAction :: _ | |
| handleAction = case _ of | |
| Increment -> | |
| Store.updateStore StoreIncrement | |
| Decrement -> | |
| Store.updateStore StoreDecrement | |
| Receive input -> | |
| H.put $ deriveState input |
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