Remove ActionDefinition runner boilerplate

Guide/view.markdown

@@ -660,9 +660,6 @@ instance JsonView IndexView where
 instance Controller PostsController where
     type ControllerAction PostsController = ActionDefinition PostsController
 
-    runControllerAction actionDefinition =
-        runActionDefinition actionDefinition
-
     action PostsAction =
         endpoint
             |> responseView @IndexView

ihp/IHP/Controller/ActionDefinition.hs

@@ -61,6 +61,10 @@ data ActionDefinition controller = ActionDefinition
     , runActionDefinition :: ControllerAction' controller
     }
 
+instance RunControllerAction controller (ActionDefinition controller) where
+    runControllerActionDefault = runActionDefinition
+    {-# INLINABLE runControllerActionDefault #-}
+
 instance
     ( Data controller
     , Controller controller

ihp/IHP/ControllerSupport.hs

@@ -1,8 +1,9 @@
-{-# LANGUAGE TypeSynonymInstances, FlexibleInstances, TypeFamilies, ConstrainedClassMethods, ScopedTypeVariables, FunctionalDependencies, AllowAmbiguousTypes, RankNTypes, DefaultSignatures #-}
+{-# LANGUAGE TypeSynonymInstances, FlexibleInstances, TypeFamilies, ConstrainedClassMethods, ScopedTypeVariables, FunctionalDependencies, AllowAmbiguousTypes, RankNTypes, DefaultSignatures, MultiParamTypeClasses, TypeApplications #-}
 
 module IHP.ControllerSupport
 ( Action'
 , ControllerAction'
+, RunControllerAction (..)
 , (|>)
 , getRequestBody
 , getRequestPath
@@ -82,6 +83,18 @@ type ControllerAction' controller =
     ) =>
     IO ResponseReceived
 
+-- | Runs a controller's 'ControllerAction' value.
+--
+-- This lets action representations such as 'IHP.Controller.ActionDefinition.ActionDefinition'
+-- plug into the normal controller dispatch without requiring each controller instance to
+-- repeat the same 'runControllerAction' implementation.
+class RunControllerAction controller action where
+    runControllerActionDefault :: (?context :: Context.ControllerContext, ?modelContext :: ModelContext, ?theAction :: controller, ?respond :: Respond, ?request :: Request) => action -> IO ResponseReceived
+
+instance RunControllerAction controller (IO ResponseReceived) where
+    runControllerActionDefault controllerAction = controllerAction
+    {-# INLINABLE runControllerActionDefault #-}
+
 class (Show controller, Eq controller) => Controller controller where
     type ControllerAction controller :: Type
     type ControllerAction controller = IO ResponseReceived
@@ -93,8 +106,8 @@ class (Show controller, Eq controller) => Controller controller where
     action :: (?context :: Context.ControllerContext, ?modelContext :: ModelContext, ?theAction :: controller, ?respond :: Respond, ?request :: Request) => controller -> ControllerAction controller
 
     runControllerAction :: (?context :: Context.ControllerContext, ?modelContext :: ModelContext, ?theAction :: controller, ?respond :: Respond, ?request :: Request) => ControllerAction controller -> IO ResponseReceived
-    default runControllerAction :: (ControllerAction controller ~ IO ResponseReceived, ?context :: Context.ControllerContext, ?modelContext :: ModelContext, ?theAction :: controller, ?respond :: Respond, ?request :: Request) => ControllerAction controller -> IO ResponseReceived
-    runControllerAction controllerAction = controllerAction
+    default runControllerAction :: (RunControllerAction controller (ControllerAction controller), ?context :: Context.ControllerContext, ?modelContext :: ModelContext, ?theAction :: controller, ?respond :: Respond, ?request :: Request) => ControllerAction controller -> IO ResponseReceived
+    runControllerAction = runControllerActionDefault @controller
     {-# INLINABLE runControllerAction #-}
 
 class InitControllerContext application where

ihp/Test/Test/OpenApiSupportSpec.hs

@@ -154,8 +154,6 @@ instance JsonView AckView where
 instance Controller DocumentedController where
     type ControllerAction DocumentedController = ActionDefinition DocumentedController
 
-    runControllerAction actionDefinition = runActionDefinition actionDefinition
-
     action ShowBandAction{..} =
         endpoint
             |> responseView @BandView
@@ -177,16 +175,13 @@ instance Controller CustomRouteController where
 instance Controller DocumentedCustomPathController where
     type ControllerAction DocumentedCustomPathController = ActionDefinition DocumentedCustomPathController
 
-    runControllerAction actionDefinition = runActionDefinition actionDefinition
-
     action ShowDocumentedCustomPathAction{..} =
         endpoint
             |> responseView @DocumentedCustomPathView
             |> handle (pure DocumentedCustomPathView{..})
 
 instance Controller CrudNamedApiController where
     type ControllerAction CrudNamedApiController = ActionDefinition CrudNamedApiController
-    runControllerAction actionDefinition = runActionDefinition actionDefinition
 
     action CreateApiSessionAction =
         endpoint