我的目标是调用远程api以便在启动时填充Purescript Thermite组件，为此我需要（我认为） componentDidMount 事件处理程序，它不能直接在Thermite上使用，但是由较低级别暴露的反应绑定 Purescript-React
所以我尝试使用 createReactSpec 函数添加 componentDidMount 事件监听器，但是我得到一个涉及刚性类型变量的类型不匹配我不明白（我对purescript / haskell很新）。
感谢您的帮助
以下是代码：
module Main where
import Prelude
import Control.Monad.Eff (Eff)
import DOM (DOM) as DOM
import DOM.HTML (window) as DOM
import DOM.HTML.Document (body) as DOM
import DOM.HTML.Types (htmlElementToElement) as DOM
import DOM.HTML.Window (document) as DOM
import Data.Foldable (traverse_)
import React (ComponentDidMount, createClass, createFactory, transformState)
import React.DOM as R
import ReactDOM (render)
import Thermite as T
-- MAIN
main :: Eff (dom :: DOM.DOM ) Unit
main = myMain componentSpec initialState unit
-- | A default implementation of `main` which renders a component to the document body.
myMain :: forall s p a eff . T.Spec eff s p a -> s -> p -> Eff (dom :: DOM.DOM | eff) Unit
myMain spec initialState props = void do
let reactSpec = (T.createReactSpec spec initialState).spec { componentDidMount = onMount }
let component = createClass reactSpec
document <- DOM.window >>= DOM.document
container <- DOM.body document
traverse_ (render (createFactory component props) <<< DOM.htmlElementToElement) container
onMount :: forall props eff . ComponentDidMount props State eff
onMount ctx = transformState ctx (\st -> st { status = "mounted" })
-- STATE
type State = { status :: String }
initialState :: State
initialState = { status: "nothing" }
-- COMPONENT STRUCTURE
componentSpec :: T.Spec _ State _ _
componentSpec = T.simpleSpec performAction render where
render :: T.Render State _ _
render dispatch _ s _ = [
R.div' [ R.text ( s.status) ]
]
performAction :: T.PerformAction _ State _ _
performAction _ _ _ = void (T.cotransform (\state -> state { status = "something happened"} ))
错误信息：
Error found:
in module Main
at src/Main.purs line 25, column 31 - line 25, column 40
Could not match type
state4
with type
{ status :: String
}
while trying to match type ReactThis props3 state4
with type ReactThis t5
{ status :: String
}
while checking that expression reactSpec
has type { render :: ReactThis t0 t1
-> Eff
( props :: ReactProps
, refs :: ReactRefs (() :: # Control.Monad.Eff.Effect)
, state :: ReactState
( read :: Read
)
| t2
)
ReactElement
, displayName :: String
, getInitialState :: ReactThis t0 t1
-> Eff
( props :: ReactProps
, state :: ReactState (() :: # Control.Monad.Eff.Effect)
, refs :: ReactRefs (() :: # Control.Monad.Eff.Effect)
| t2
)
t1
, componentWillMount :: ReactThis t0 t1
-> Eff
( props :: ReactProps
, state :: ReactState
( read :: Read
, write :: Write
)
, refs :: ReactRefs (() :: # Control.Monad.Eff.Effect)
| t2
)
Unit
, componentDidMount :: ReactThis t0 t1
-> Eff
( props :: ReactProps
, state :: ReactState
( read :: Read
, write :: Write
)
, refs :: ReactRefs
( read :: Read
)
| t2
)
Unit
, componentWillReceiveProps :: ReactThis t0 t1
-> t0
-> Eff
( props :: ReactProps
, state :: ReactState
( read :: Read
, write :: Write
)
, refs :: ReactRefs
( read :: Read
)
| t2
)
Unit
, shouldComponentUpdate :: ReactThis t0 t1
-> t0
-> t1
-> Eff
( props :: ReactProps
, state :: ReactState
( read :: Read
, write :: Write
)
, refs :: ReactRefs
( read :: Read
)
| t2
)
Boolean
, componentWillUpdate :: ReactThis t0 t1
-> t0
-> t1
-> Eff
( props :: ReactProps
, state :: ReactState
( read :: Read
, write :: Write
)
, refs :: ReactRefs
( read :: Read
)
| t2
)
Unit
, componentDidUpdate :: ReactThis t0 t1
-> t0
-> t1
-> Eff
( props :: ReactProps
, state :: ReactState
( read :: Read
)
, refs :: ReactRefs
( read :: Read
)
| t2
)
Unit
, componentWillUnmount :: ReactThis t0 t1
-> Eff
( props :: ReactProps
, state :: ReactState
( read :: Read
)
, refs :: ReactRefs
( read :: Read
)
| t2
)
Unit
}
in value declaration myMain
where props3 is a rigid type variable
state4 is a rigid type variable
t2 is an unknown type
t1 is an unknown type
t0 is an unknown type
t5 is an unknown type
答案 0 :(得分：0)
我通过在 myMain 签名
中使用状态类型解决了我的问题我换了：
myMain :: forall s p a eff . T.Spec eff s p a -> s -> p -> Eff (dom :: DOM.DOM | eff) Unit
by：
myMain :: forall p a eff . T.Spec eff State p a -> State -> p -> Eff (dom :: DOM.DOM | eff) Unit