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| 1 | +module React.Basic.Components.Async |
| 2 | + ( async |
| 3 | + , asyncWithLoader |
| 4 | + ) where |
| 5 | + |
| 6 | +import Prelude |
| 7 | + |
| 8 | +import Data.Maybe (Maybe(..), fromMaybe) |
| 9 | +import Effect.Aff (Aff, Fiber, error, killFiber, launchAff, launchAff_) |
| 10 | +import Effect.Class (liftEffect) |
| 11 | +import React.Basic (Component, JSX, StateUpdate(..), createComponent, empty, make, send) |
| 12 | + |
| 13 | +component :: Component (Aff JSX) |
| 14 | +component = createComponent "Async" |
| 15 | + |
| 16 | +data FetchAction |
| 17 | + = ReplaceFiber (Fiber Unit) |
| 18 | + | UpdateJSX JSX |
| 19 | + |
| 20 | +async :: Aff JSX -> JSX |
| 21 | +async = asyncWithLoader empty |
| 22 | + |
| 23 | +asyncWithLoader :: JSX -> Aff JSX -> JSX |
| 24 | +asyncWithLoader loader = make component |
| 25 | + { initialState |
| 26 | + , update |
| 27 | + , render |
| 28 | + , didMount: launch |
| 29 | + -- , didUpdate: No! Implementing `didUpdate` breaks the |
| 30 | + -- Aff/Component lifecycle relationship. |
| 31 | + -- To update the Aff over time, wrap this |
| 32 | + -- component with `keyed`. |
| 33 | + , willUnmount: cleanup |
| 34 | + } |
| 35 | + where |
| 36 | + initialState = |
| 37 | + { jsx: Nothing |
| 38 | + , pendingFiber: pure unit |
| 39 | + } |
| 40 | + |
| 41 | + update { props, state } = case _ of |
| 42 | + ReplaceFiber newFiber -> |
| 43 | + UpdateAndSideEffects |
| 44 | + state { jsx = Nothing, pendingFiber = newFiber } |
| 45 | + \_ -> kill state.pendingFiber |
| 46 | + |
| 47 | + UpdateJSX jsx -> |
| 48 | + Update |
| 49 | + state { jsx = Just jsx } |
| 50 | + |
| 51 | + render self = |
| 52 | + fromMaybe loader self.state.jsx |
| 53 | + |
| 54 | + launch self = do |
| 55 | + fiber <- launchAff do |
| 56 | + jsx <- self.props |
| 57 | + liftEffect $ send self $ UpdateJSX jsx |
| 58 | + send self $ ReplaceFiber fiber |
| 59 | + |
| 60 | + cleanup self = |
| 61 | + kill self.state.pendingFiber |
| 62 | + |
| 63 | + kill = |
| 64 | + launchAff_ <<< killFiber (error "Cancelled") |
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