Fix useSelector Hook never sees the initialStore (#19)

Co-authored-by: Alex Valdetaro <avaldetaro@snapchat.com>

Author: xvaldetaro

example/basic-hooks/Basic/Counter.purs example/basic-hooks/Hooks/Counter.pursexample/basic-hooks/Basic/Counter.purs renamed to example/basic-hooks/Hooks/Counter.purs

@@ -2,8 +2,8 @@ module Hooks.Counter where
 
 import Prelude
 
-import Basic.Store as BS
-import Data.Maybe (fromMaybe)
+import Hooks.Store as HS
+import Data.Maybe (Maybe(..))
 import Halogen as H
 import Halogen.HTML as HH
 import Halogen.HTML.Events as HE
@@ -14,18 +14,20 @@ import Halogen.Store.UseSelector (useSelector)
 
 component
   :: forall query input output m
-   . MonadStore BS.Action BS.Store m
+   . MonadStore HS.Action HS.Store m
   => H.Component query input output m
 component = Hooks.component \_ _ -> Hooks.do
   count <- useSelector $ selectEq _.count
   Hooks.pure do
-    let cnt = fromMaybe 0 count
-    HH.div_
-      [ HH.button
-          [ HE.onClick \_ -> updateStore BS.Increment ]
-          [ HH.text "Increment" ]
-      , HH.text $ " Count: " <> show cnt <> " "
-      , HH.button
-          [ HE.onClick \_ -> updateStore BS.Decrement ]
-          [ HH.text "Decrement" ]
-      ]
+    case count of
+      Nothing -> HH.text ""
+      Just cnt ->
+        HH.div_
+          [ HH.button
+              [ HE.onClick \_ -> updateStore HS.Increment ]
+              [ HH.text "Increment" ]
+          , HH.text $ " Count: " <> show cnt <> " "
+          , HH.button
+              [ HE.onClick \_ -> updateStore HS.Decrement ]
+              [ HH.text "Decrement" ]
+          ]

example/basic-hooks/Basic/Main.purs example/basic-hooks/Hooks/Main.pursexample/basic-hooks/Basic/Main.purs renamed to example/basic-hooks/Hooks/Main.purs

@@ -2,8 +2,8 @@ module Hooks.Main where
 
 import Prelude
 
-import Basic.Counter as Counter
-import Basic.Store as BS
+import Hooks.Counter as Counter
+import Hooks.Store as HS
 import Effect (Effect)
 import Effect.Aff (launchAff_)
 import Halogen.Aff as HA
@@ -13,5 +13,5 @@ import Halogen.VDom.Driver (runUI)
 main :: Effect Unit
 main = launchAff_ do
   body <- HA.awaitBody
-  root <- runStoreT BS.initialStore BS.reduce Counter.component
+  root <- runStoreT HS.initialStore HS.reduce Counter.component
   void $ runUI root unit body

example/basic-hooks/Basic/Store.purs example/basic-hooks/Hooks/Store.pursexample/basic-hooks/Basic/Store.purs renamed to example/basic-hooks/Hooks/Store.purs

@@ -6,7 +6,7 @@ import Data.Maybe (Maybe(..))
 import Data.Tuple.Nested ((/\))
 import Halogen.Hooks (class HookNewtype, type (<>), Hook, UseEffect, UseState)
 import Halogen.Hooks as Hooks
-import Halogen.Store.Monad (class MonadStore, emitSelected)
+import Halogen.Store.Monad (class MonadStore, emitSelected, getStore)
 import Halogen.Store.Select (Selector(..))
 
 foreign import data UseSelector :: Type -> Type -> Type -> Hooks.HookType
@@ -30,6 +30,8 @@ useSelector (Selector selector) = Hooks.wrap hook
     Hooks.useLifecycleEffect do
       emitter <- emitSelected (Selector selector)
       subscriptionId <- Hooks.subscribe $ map (Hooks.put ctxId <<< Just) emitter
+      initialCtx <- map selector.select getStore
+      Hooks.put ctxId $ Just initialCtx
       pure $ Just $ Hooks.unsubscribe subscriptionId
 
     Hooks.pure ctx