My goal is to call a remote api in order to populate a Purescript Thermite component at startup, for this I need (I think) the componentDidMount event handler which is not directly available on Thermite but is exposed by the lower level react bindings Purescript-React
So I try to use the createReactSpec function to add the componentDidMount event listener but I get a type mismatch involving a rigid type variable that I don't understand (I'm quite new to purescript / haskell).
Thanks for your help
Here is the code :
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"} ))
And the error message :
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
