diff --git a/examples/client-rendering/src/routes/Root__Todos__ByStatus_route_renderer.res b/examples/client-rendering/src/routes/Root__Todos__ByStatus_route_renderer.res
index f618a5a..3686a9d 100644
--- a/examples/client-rendering/src/routes/Root__Todos__ByStatus_route_renderer.res
+++ b/examples/client-rendering/src/routes/Root__Todos__ByStatus_route_renderer.res
@@ -1,8 +1,8 @@
-let renderer = Routes.Root.Todos.ByStatus.Route.makeRenderer(
-  ~prepare=_props => {
+let renderer: Routes.Root.Todos.ByStatus.Route.routeRenderer<'prepared> = {
+  prepare: _props => {
     ()
   },
-  ~render=_props => {
+  render: _props => {
     React.null
   },
-)
+}
diff --git a/examples/client-rendering/src/routes/Root__Todos__Single_route_renderer.res b/examples/client-rendering/src/routes/Root__Todos__Single_route_renderer.res
index 388b6ff..e267c53 100644
--- a/examples/client-rendering/src/routes/Root__Todos__Single_route_renderer.res
+++ b/examples/client-rendering/src/routes/Root__Todos__Single_route_renderer.res
@@ -1,5 +1,5 @@
-let renderer = Routes.Root.Todos.Single.Route.makeRenderer(
-  ~prepare=({environment, showMore, todoId}) => {
+let renderer: Routes.Root.Todos.Single.Route.routeRenderer<'prepared> = {
+  prepare: ({environment, params: {showMore, todoId}}) => {
     SingleTodoQuery_graphql.load(
       ~environment,
       ~fetchPolicy=StoreOrNetwork,
@@ -9,7 +9,7 @@ let renderer = Routes.Root.Todos.Single.Route.makeRenderer(
       },
     )
   },
-  ~render=({prepared}) => {
+  render: ({prepared}) => {
     <SingleTodo queryRef=prepared />
   },
-)
+}
diff --git a/examples/client-rendering/src/routes/Root__Todos_route_renderer.res b/examples/client-rendering/src/routes/Root__Todos_route_renderer.res
index 2d9ca07..fe3ef92 100644
--- a/examples/client-rendering/src/routes/Root__Todos_route_renderer.res
+++ b/examples/client-rendering/src/routes/Root__Todos_route_renderer.res
@@ -1,8 +1,8 @@
-let renderer = Route__Root__Todos_route.makeRenderer(
-  ~prepare=({environment}) => {
+let renderer: Route__Root__Todos_route.routeRenderer<'prepared> = {
+  prepare: ({environment}) => {
     TodosListQuery_graphql.load(~environment, ~fetchPolicy=StoreOrNetwork, ~variables=())
   },
-  ~render=({prepared, childRoutes}) => {
+  render: ({prepared, childRoutes}) => {
     <TodosList queryRef=prepared> {childRoutes} </TodosList>
   },
-)
+}
diff --git a/examples/client-rendering/src/routes/Root_route_renderer.res b/examples/client-rendering/src/routes/Root_route_renderer.res
index 8f3de6c..09b8b57 100644
--- a/examples/client-rendering/src/routes/Root_route_renderer.res
+++ b/examples/client-rendering/src/routes/Root_route_renderer.res
@@ -1,8 +1,8 @@
-let renderer = Route__Root_route.makeRenderer(
-  ~prepare=({environment}) => {
+let renderer: Routes.Root.Route.routeRenderer<'prepared> = {
+  prepare: ({environment}) => {
     LayoutQuery_graphql.load(~environment, ~variables=(), ~fetchPolicy=StoreOrNetwork)
   },
-  ~render=props => {
+  render: props => {
     <Layout queryRef=props.prepared> {props.childRoutes} </Layout>
   },
-)
+}
diff --git a/examples/client-rendering/src/routes/__generated__/RouteDeclarations.res b/examples/client-rendering/src/routes/__generated__/RouteDeclarations.res
index 5ad1d7d..90457bd 100644
--- a/examples/client-rendering/src/routes/__generated__/RouteDeclarations.res
+++ b/examples/client-rendering/src/routes/__generated__/RouteDeclarations.res
@@ -1,8 +1,6 @@
 
 open RelayRouter__Internal__DeclarationsSupport
 
-external unsafe_toPrepareProps: 'any => prepareProps = "%identity"
-
 let loadedRouteRenderers: Belt.HashMap.String.t<loadedRouteRenderer> = Belt.HashMap.String.make(
   ~hintSize=4,
 )
@@ -13,20 +11,23 @@ let make = (~prepareDisposeTimeout=5 * 60 * 1000): array<RelayRouter.Types.route
   [
       {
     let routeName = "Root"
-    let loadRouteRenderer = () => (() => Js.import(Root_route_renderer.renderer))->Obj.magic->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
+    let loadRouteRenderer = () => (() => Js.import(Root_route_renderer.renderer))->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
     let makePrepareProps = (. 
     ~environment: RescriptRelay.Environment.t,
     ~pathParams: Js.Dict.t<string>,
     ~queryParams: RelayRouter.Bindings.QueryParams.t,
     ~location: RelayRouter.History.location,
-  ): prepareProps => {
+  )  => {
     ignore(pathParams)
     ignore(queryParams)
     let prepareProps: Route__Root_route.Internal.prepareProps =   {
       environment: environment,
   
       location: location,
+  
+      params: {
     }
+  }
     prepareProps->unsafe_toPrepareProps
   }
   
@@ -82,20 +83,23 @@ let make = (~prepareDisposeTimeout=5 * 60 * 1000): array<RelayRouter.Types.route
       ),
       children: [    {
         let routeName = "Root__Todos"
-        let loadRouteRenderer = () => (() => Js.import(Root__Todos_route_renderer.renderer))->Obj.magic->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
+        let loadRouteRenderer = () => (() => Js.import(Root__Todos_route_renderer.renderer))->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
         let makePrepareProps = (. 
         ~environment: RescriptRelay.Environment.t,
         ~pathParams: Js.Dict.t<string>,
         ~queryParams: RelayRouter.Bindings.QueryParams.t,
         ~location: RelayRouter.History.location,
-      ): prepareProps => {
+      )  => {
         ignore(pathParams)
         let prepareProps: Route__Root__Todos_route.Internal.prepareProps =   {
           environment: environment,
       
           location: location,
+      
+          params: {
           statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
         }
+      }
         prepareProps->unsafe_toPrepareProps
       }
       
@@ -150,20 +154,23 @@ let make = (~prepareDisposeTimeout=5 * 60 * 1000): array<RelayRouter.Types.route
           ),
           children: [      {
               let routeName = "Root__Todos__ByStatus"
-              let loadRouteRenderer = () => (() => Js.import(Root__Todos__ByStatus_route_renderer.renderer))->Obj.magic->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
+              let loadRouteRenderer = () => (() => Js.import(Root__Todos__ByStatus_route_renderer.renderer))->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
               let makePrepareProps = (. 
               ~environment: RescriptRelay.Environment.t,
               ~pathParams: Js.Dict.t<string>,
               ~queryParams: RelayRouter.Bindings.QueryParams.t,
               ~location: RelayRouter.History.location,
-            ): prepareProps => {
+            )  => {
               let prepareProps: Route__Root__Todos__ByStatus_route.Internal.prepareProps =   {
                 environment: environment,
             
                 location: location,
+            
+                params: {
                 byStatus: pathParams->Js.Dict.unsafeGet("byStatus")->Obj.magic,
                 statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
               }
+            }
               prepareProps->unsafe_toPrepareProps
             }
             
@@ -220,17 +227,19 @@ let make = (~prepareDisposeTimeout=5 * 60 * 1000): array<RelayRouter.Types.route
             },
             {
               let routeName = "Root__Todos__Single"
-              let loadRouteRenderer = () => (() => Js.import(Root__Todos__Single_route_renderer.renderer))->Obj.magic->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
+              let loadRouteRenderer = () => (() => Js.import(Root__Todos__Single_route_renderer.renderer))->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
               let makePrepareProps = (. 
               ~environment: RescriptRelay.Environment.t,
               ~pathParams: Js.Dict.t<string>,
               ~queryParams: RelayRouter.Bindings.QueryParams.t,
               ~location: RelayRouter.History.location,
-            ): prepareProps => {
+            )  => {
               let prepareProps: Route__Root__Todos__Single_route.Internal.prepareProps =   {
                 environment: environment,
             
                 location: location,
+            
+                params: {
                 todoId: pathParams->Js.Dict.unsafeGet("todoId"),
                 statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
                 showMore: queryParams->RelayRouter.Bindings.QueryParams.getParamByKey("showMore")->Belt.Option.flatMap(value => switch value {
@@ -239,6 +248,7 @@ let make = (~prepareDisposeTimeout=5 * 60 * 1000): array<RelayRouter.Types.route
                   | _ => None
                   }),
               }
+            }
               prepareProps->unsafe_toPrepareProps
             }
             
diff --git a/examples/client-rendering/src/routes/__generated__/Route__Root__Todos__ByStatus_route.res b/examples/client-rendering/src/routes/__generated__/Route__Root__Todos__ByStatus_route.res
index 214b1cd..d2fca3a 100644
--- a/examples/client-rendering/src/routes/__generated__/Route__Root__Todos__ByStatus_route.res
+++ b/examples/client-rendering/src/routes/__generated__/Route__Root__Todos__ByStatus_route.res
@@ -2,44 +2,32 @@
 // This file is autogenerated from `todoRoutes.json`, do not edit manually.
 module Internal = {
   @live
-  type prepareProps = {
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
+  type params = {
     byStatus: [#completed | #notCompleted],
     statuses: option<array<TodoStatus.t>>,
   }
 
   @live
-  type renderProps<'prepared> = {
-    childRoutes: React.element,
-    prepared: 'prepared,
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
-    byStatus: [#completed | #notCompleted],
-    statuses: option<array<TodoStatus.t>>,
-  }
+  type prepareProps = RelayRouter__Internal__DeclarationsSupport.prepareProps<params>
 
-  @live
-  type renderers<'prepared> = {
-    prepare: prepareProps => 'prepared,
-    prepareCode: option<(. prepareProps) => array<RelayRouter.Types.preloadAsset>>,
-    render: renderProps<'prepared> => React.element,
-  }
   @live
   let makePrepareProps = (. 
     ~environment: RescriptRelay.Environment.t,
     ~pathParams: Js.Dict.t<string>,
     ~queryParams: RelayRouter.Bindings.QueryParams.t,
     ~location: RelayRouter.History.location,
-  ): prepareProps => {
+  ): prepareProps  => {
     {
       environment: environment,
   
       location: location,
+  
+      params: {
       byStatus: pathParams->Js.Dict.unsafeGet("byStatus")->Obj.magic,
       statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
     }
   }
+  }
 
 }
 
@@ -175,9 +163,4 @@ let useIsRouteActive = (~exact=false) => {
   React.useMemo2(() => location->isRouteActive(~exact), (location, exact))
 }
 
-@obj
-external makeRenderer: (
-  ~prepare: Internal.prepareProps => 'prepared,
-  ~prepareCode: Internal.prepareProps => array<RelayRouter.Types.preloadAsset>=?,
-  ~render: Internal.renderProps<'prepared> => React.element,
-) => Internal.renderers<'prepared> = ""
\ No newline at end of file
+  type routeRenderer<'prepared> = RelayRouter__Internal__DeclarationsSupport.RouteRenderer.t<Internal.params, 'prepared>
diff --git a/examples/client-rendering/src/routes/__generated__/Route__Root__Todos__Single_route.res b/examples/client-rendering/src/routes/__generated__/Route__Root__Todos__Single_route.res
index 4ad6c7a..e9bc4f7 100644
--- a/examples/client-rendering/src/routes/__generated__/Route__Root__Todos__Single_route.res
+++ b/examples/client-rendering/src/routes/__generated__/Route__Root__Todos__Single_route.res
@@ -2,42 +2,28 @@
 // This file is autogenerated from `todoRoutes.json`, do not edit manually.
 module Internal = {
   @live
-  type prepareProps = {
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
+  type params = {
     todoId: string,
     statuses: option<array<TodoStatus.t>>,
     showMore: option<bool>,
   }
 
   @live
-  type renderProps<'prepared> = {
-    childRoutes: React.element,
-    prepared: 'prepared,
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
-    todoId: string,
-    statuses: option<array<TodoStatus.t>>,
-    showMore: option<bool>,
-  }
+  type prepareProps = RelayRouter__Internal__DeclarationsSupport.prepareProps<params>
 
-  @live
-  type renderers<'prepared> = {
-    prepare: prepareProps => 'prepared,
-    prepareCode: option<(. prepareProps) => array<RelayRouter.Types.preloadAsset>>,
-    render: renderProps<'prepared> => React.element,
-  }
   @live
   let makePrepareProps = (. 
     ~environment: RescriptRelay.Environment.t,
     ~pathParams: Js.Dict.t<string>,
     ~queryParams: RelayRouter.Bindings.QueryParams.t,
     ~location: RelayRouter.History.location,
-  ): prepareProps => {
+  ): prepareProps  => {
     {
       environment: environment,
   
       location: location,
+  
+      params: {
       todoId: pathParams->Js.Dict.unsafeGet("todoId"),
       statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
       showMore: queryParams->RelayRouter.Bindings.QueryParams.getParamByKey("showMore")->Belt.Option.flatMap(value => switch value {
@@ -47,6 +33,7 @@ module Internal = {
         }),
     }
   }
+  }
 
 }
 
@@ -194,9 +181,4 @@ let useIsRouteActive = (~exact=false) => {
   React.useMemo2(() => location->isRouteActive(~exact), (location, exact))
 }
 
-@obj
-external makeRenderer: (
-  ~prepare: Internal.prepareProps => 'prepared,
-  ~prepareCode: Internal.prepareProps => array<RelayRouter.Types.preloadAsset>=?,
-  ~render: Internal.renderProps<'prepared> => React.element,
-) => Internal.renderers<'prepared> = ""
\ No newline at end of file
+  type routeRenderer<'prepared> = RelayRouter__Internal__DeclarationsSupport.RouteRenderer.t<Internal.params, 'prepared>
diff --git a/examples/client-rendering/src/routes/__generated__/Route__Root__Todos_route.res b/examples/client-rendering/src/routes/__generated__/Route__Root__Todos_route.res
index 69c2246..6043019 100644
--- a/examples/client-rendering/src/routes/__generated__/Route__Root__Todos_route.res
+++ b/examples/client-rendering/src/routes/__generated__/Route__Root__Todos_route.res
@@ -2,42 +2,31 @@
 // This file is autogenerated from `todoRoutes.json`, do not edit manually.
 module Internal = {
   @live
-  type prepareProps = {
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
+  type params = {
     statuses: option<array<TodoStatus.t>>,
   }
 
   @live
-  type renderProps<'prepared> = {
-    childRoutes: React.element,
-    prepared: 'prepared,
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
-    statuses: option<array<TodoStatus.t>>,
-  }
+  type prepareProps = RelayRouter__Internal__DeclarationsSupport.prepareProps<params>
 
-  @live
-  type renderers<'prepared> = {
-    prepare: prepareProps => 'prepared,
-    prepareCode: option<(. prepareProps) => array<RelayRouter.Types.preloadAsset>>,
-    render: renderProps<'prepared> => React.element,
-  }
   @live
   let makePrepareProps = (. 
     ~environment: RescriptRelay.Environment.t,
     ~pathParams: Js.Dict.t<string>,
     ~queryParams: RelayRouter.Bindings.QueryParams.t,
     ~location: RelayRouter.History.location,
-  ): prepareProps => {
+  ): prepareProps  => {
     ignore(pathParams)
     {
       environment: environment,
   
       location: location,
+  
+      params: {
       statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
     }
   }
+  }
 
 }
 
@@ -192,9 +181,4 @@ let useActiveSubRoute = (): option<[#ByStatus | #Single]> => {
   }, [location])
 }
 
-@obj
-external makeRenderer: (
-  ~prepare: Internal.prepareProps => 'prepared,
-  ~prepareCode: Internal.prepareProps => array<RelayRouter.Types.preloadAsset>=?,
-  ~render: Internal.renderProps<'prepared> => React.element,
-) => Internal.renderers<'prepared> = ""
\ No newline at end of file
+  type routeRenderer<'prepared> = RelayRouter__Internal__DeclarationsSupport.RouteRenderer.t<Internal.params, 'prepared>
diff --git a/examples/client-rendering/src/routes/__generated__/Route__Root_route.res b/examples/client-rendering/src/routes/__generated__/Route__Root_route.res
index c069fa0..4d5247e 100644
--- a/examples/client-rendering/src/routes/__generated__/Route__Root_route.res
+++ b/examples/client-rendering/src/routes/__generated__/Route__Root_route.res
@@ -2,40 +2,30 @@
 // This file is autogenerated from `routes.json`, do not edit manually.
 module Internal = {
   @live
-  type prepareProps = {
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
+  type params = {
   }
 
   @live
-  type renderProps<'prepared> = {
-    childRoutes: React.element,
-    prepared: 'prepared,
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
-  }
+  type prepareProps = RelayRouter__Internal__DeclarationsSupport.prepareProps<params>
 
-  @live
-  type renderers<'prepared> = {
-    prepare: prepareProps => 'prepared,
-    prepareCode: option<(. prepareProps) => array<RelayRouter.Types.preloadAsset>>,
-    render: renderProps<'prepared> => React.element,
-  }
   @live
   let makePrepareProps = (. 
     ~environment: RescriptRelay.Environment.t,
     ~pathParams: Js.Dict.t<string>,
     ~queryParams: RelayRouter.Bindings.QueryParams.t,
     ~location: RelayRouter.History.location,
-  ): prepareProps => {
+  ): prepareProps  => {
     ignore(pathParams)
     ignore(queryParams)
     {
       environment: environment,
   
       location: location,
+  
+      params: {
     }
   }
+  }
 
 }
 
@@ -80,9 +70,4 @@ let useActiveSubRoute = (): option<[#Todos]> => {
   }, [location])
 }
 
-@obj
-external makeRenderer: (
-  ~prepare: Internal.prepareProps => 'prepared,
-  ~prepareCode: Internal.prepareProps => array<RelayRouter.Types.preloadAsset>=?,
-  ~render: Internal.renderProps<'prepared> => React.element,
-) => Internal.renderers<'prepared> = ""
\ No newline at end of file
+  type routeRenderer<'prepared> = RelayRouter__Internal__DeclarationsSupport.RouteRenderer.t<Internal.params, 'prepared>
diff --git a/examples/express/src/routes/Root__Todos__ByStatus_route_renderer.res b/examples/express/src/routes/Root__Todos__ByStatus_route_renderer.res
index f618a5a..3686a9d 100644
--- a/examples/express/src/routes/Root__Todos__ByStatus_route_renderer.res
+++ b/examples/express/src/routes/Root__Todos__ByStatus_route_renderer.res
@@ -1,8 +1,8 @@
-let renderer = Routes.Root.Todos.ByStatus.Route.makeRenderer(
-  ~prepare=_props => {
+let renderer: Routes.Root.Todos.ByStatus.Route.routeRenderer<'prepared> = {
+  prepare: _props => {
     ()
   },
-  ~render=_props => {
+  render: _props => {
     React.null
   },
-)
+}
diff --git a/examples/express/src/routes/Root__Todos__Single_route_renderer.res b/examples/express/src/routes/Root__Todos__Single_route_renderer.res
index 388b6ff..e267c53 100644
--- a/examples/express/src/routes/Root__Todos__Single_route_renderer.res
+++ b/examples/express/src/routes/Root__Todos__Single_route_renderer.res
@@ -1,5 +1,5 @@
-let renderer = Routes.Root.Todos.Single.Route.makeRenderer(
-  ~prepare=({environment, showMore, todoId}) => {
+let renderer: Routes.Root.Todos.Single.Route.routeRenderer<'prepared> = {
+  prepare: ({environment, params: {showMore, todoId}}) => {
     SingleTodoQuery_graphql.load(
       ~environment,
       ~fetchPolicy=StoreOrNetwork,
@@ -9,7 +9,7 @@ let renderer = Routes.Root.Todos.Single.Route.makeRenderer(
       },
     )
   },
-  ~render=({prepared}) => {
+  render: ({prepared}) => {
     <SingleTodo queryRef=prepared />
   },
-)
+}
diff --git a/examples/express/src/routes/Root__Todos_route_renderer.res b/examples/express/src/routes/Root__Todos_route_renderer.res
index 2d9ca07..22a9c9c 100644
--- a/examples/express/src/routes/Root__Todos_route_renderer.res
+++ b/examples/express/src/routes/Root__Todos_route_renderer.res
@@ -1,8 +1,8 @@
-let renderer = Route__Root__Todos_route.makeRenderer(
-  ~prepare=({environment}) => {
+let renderer: Routes.Root.Todos.Route.routeRenderer<'prepared> = {
+  prepare: ({environment}) => {
     TodosListQuery_graphql.load(~environment, ~fetchPolicy=StoreOrNetwork, ~variables=())
   },
-  ~render=({prepared, childRoutes}) => {
+  render: ({prepared, childRoutes}) => {
     <TodosList queryRef=prepared> {childRoutes} </TodosList>
   },
-)
+}
diff --git a/examples/express/src/routes/Root_route_renderer.res b/examples/express/src/routes/Root_route_renderer.res
index 8f3de6c..09b8b57 100644
--- a/examples/express/src/routes/Root_route_renderer.res
+++ b/examples/express/src/routes/Root_route_renderer.res
@@ -1,8 +1,8 @@
-let renderer = Route__Root_route.makeRenderer(
-  ~prepare=({environment}) => {
+let renderer: Routes.Root.Route.routeRenderer<'prepared> = {
+  prepare: ({environment}) => {
     LayoutQuery_graphql.load(~environment, ~variables=(), ~fetchPolicy=StoreOrNetwork)
   },
-  ~render=props => {
+  render: props => {
     <Layout queryRef=props.prepared> {props.childRoutes} </Layout>
   },
-)
+}
diff --git a/examples/express/src/routes/__generated__/RouteDeclarations.res b/examples/express/src/routes/__generated__/RouteDeclarations.res
index 5ad1d7d..90457bd 100644
--- a/examples/express/src/routes/__generated__/RouteDeclarations.res
+++ b/examples/express/src/routes/__generated__/RouteDeclarations.res
@@ -1,8 +1,6 @@
 
 open RelayRouter__Internal__DeclarationsSupport
 
-external unsafe_toPrepareProps: 'any => prepareProps = "%identity"
-
 let loadedRouteRenderers: Belt.HashMap.String.t<loadedRouteRenderer> = Belt.HashMap.String.make(
   ~hintSize=4,
 )
@@ -13,20 +11,23 @@ let make = (~prepareDisposeTimeout=5 * 60 * 1000): array<RelayRouter.Types.route
   [
       {
     let routeName = "Root"
-    let loadRouteRenderer = () => (() => Js.import(Root_route_renderer.renderer))->Obj.magic->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
+    let loadRouteRenderer = () => (() => Js.import(Root_route_renderer.renderer))->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
     let makePrepareProps = (. 
     ~environment: RescriptRelay.Environment.t,
     ~pathParams: Js.Dict.t<string>,
     ~queryParams: RelayRouter.Bindings.QueryParams.t,
     ~location: RelayRouter.History.location,
-  ): prepareProps => {
+  )  => {
     ignore(pathParams)
     ignore(queryParams)
     let prepareProps: Route__Root_route.Internal.prepareProps =   {
       environment: environment,
   
       location: location,
+  
+      params: {
     }
+  }
     prepareProps->unsafe_toPrepareProps
   }
   
@@ -82,20 +83,23 @@ let make = (~prepareDisposeTimeout=5 * 60 * 1000): array<RelayRouter.Types.route
       ),
       children: [    {
         let routeName = "Root__Todos"
-        let loadRouteRenderer = () => (() => Js.import(Root__Todos_route_renderer.renderer))->Obj.magic->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
+        let loadRouteRenderer = () => (() => Js.import(Root__Todos_route_renderer.renderer))->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
         let makePrepareProps = (. 
         ~environment: RescriptRelay.Environment.t,
         ~pathParams: Js.Dict.t<string>,
         ~queryParams: RelayRouter.Bindings.QueryParams.t,
         ~location: RelayRouter.History.location,
-      ): prepareProps => {
+      )  => {
         ignore(pathParams)
         let prepareProps: Route__Root__Todos_route.Internal.prepareProps =   {
           environment: environment,
       
           location: location,
+      
+          params: {
           statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
         }
+      }
         prepareProps->unsafe_toPrepareProps
       }
       
@@ -150,20 +154,23 @@ let make = (~prepareDisposeTimeout=5 * 60 * 1000): array<RelayRouter.Types.route
           ),
           children: [      {
               let routeName = "Root__Todos__ByStatus"
-              let loadRouteRenderer = () => (() => Js.import(Root__Todos__ByStatus_route_renderer.renderer))->Obj.magic->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
+              let loadRouteRenderer = () => (() => Js.import(Root__Todos__ByStatus_route_renderer.renderer))->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
               let makePrepareProps = (. 
               ~environment: RescriptRelay.Environment.t,
               ~pathParams: Js.Dict.t<string>,
               ~queryParams: RelayRouter.Bindings.QueryParams.t,
               ~location: RelayRouter.History.location,
-            ): prepareProps => {
+            )  => {
               let prepareProps: Route__Root__Todos__ByStatus_route.Internal.prepareProps =   {
                 environment: environment,
             
                 location: location,
+            
+                params: {
                 byStatus: pathParams->Js.Dict.unsafeGet("byStatus")->Obj.magic,
                 statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
               }
+            }
               prepareProps->unsafe_toPrepareProps
             }
             
@@ -220,17 +227,19 @@ let make = (~prepareDisposeTimeout=5 * 60 * 1000): array<RelayRouter.Types.route
             },
             {
               let routeName = "Root__Todos__Single"
-              let loadRouteRenderer = () => (() => Js.import(Root__Todos__Single_route_renderer.renderer))->Obj.magic->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
+              let loadRouteRenderer = () => (() => Js.import(Root__Todos__Single_route_renderer.renderer))->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
               let makePrepareProps = (. 
               ~environment: RescriptRelay.Environment.t,
               ~pathParams: Js.Dict.t<string>,
               ~queryParams: RelayRouter.Bindings.QueryParams.t,
               ~location: RelayRouter.History.location,
-            ): prepareProps => {
+            )  => {
               let prepareProps: Route__Root__Todos__Single_route.Internal.prepareProps =   {
                 environment: environment,
             
                 location: location,
+            
+                params: {
                 todoId: pathParams->Js.Dict.unsafeGet("todoId"),
                 statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
                 showMore: queryParams->RelayRouter.Bindings.QueryParams.getParamByKey("showMore")->Belt.Option.flatMap(value => switch value {
@@ -239,6 +248,7 @@ let make = (~prepareDisposeTimeout=5 * 60 * 1000): array<RelayRouter.Types.route
                   | _ => None
                   }),
               }
+            }
               prepareProps->unsafe_toPrepareProps
             }
             
diff --git a/examples/express/src/routes/__generated__/Route__Root__Todos__ByStatus_route.res b/examples/express/src/routes/__generated__/Route__Root__Todos__ByStatus_route.res
index 214b1cd..d2fca3a 100644
--- a/examples/express/src/routes/__generated__/Route__Root__Todos__ByStatus_route.res
+++ b/examples/express/src/routes/__generated__/Route__Root__Todos__ByStatus_route.res
@@ -2,44 +2,32 @@
 // This file is autogenerated from `todoRoutes.json`, do not edit manually.
 module Internal = {
   @live
-  type prepareProps = {
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
+  type params = {
     byStatus: [#completed | #notCompleted],
     statuses: option<array<TodoStatus.t>>,
   }
 
   @live
-  type renderProps<'prepared> = {
-    childRoutes: React.element,
-    prepared: 'prepared,
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
-    byStatus: [#completed | #notCompleted],
-    statuses: option<array<TodoStatus.t>>,
-  }
+  type prepareProps = RelayRouter__Internal__DeclarationsSupport.prepareProps<params>
 
-  @live
-  type renderers<'prepared> = {
-    prepare: prepareProps => 'prepared,
-    prepareCode: option<(. prepareProps) => array<RelayRouter.Types.preloadAsset>>,
-    render: renderProps<'prepared> => React.element,
-  }
   @live
   let makePrepareProps = (. 
     ~environment: RescriptRelay.Environment.t,
     ~pathParams: Js.Dict.t<string>,
     ~queryParams: RelayRouter.Bindings.QueryParams.t,
     ~location: RelayRouter.History.location,
-  ): prepareProps => {
+  ): prepareProps  => {
     {
       environment: environment,
   
       location: location,
+  
+      params: {
       byStatus: pathParams->Js.Dict.unsafeGet("byStatus")->Obj.magic,
       statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
     }
   }
+  }
 
 }
 
@@ -175,9 +163,4 @@ let useIsRouteActive = (~exact=false) => {
   React.useMemo2(() => location->isRouteActive(~exact), (location, exact))
 }
 
-@obj
-external makeRenderer: (
-  ~prepare: Internal.prepareProps => 'prepared,
-  ~prepareCode: Internal.prepareProps => array<RelayRouter.Types.preloadAsset>=?,
-  ~render: Internal.renderProps<'prepared> => React.element,
-) => Internal.renderers<'prepared> = ""
\ No newline at end of file
+  type routeRenderer<'prepared> = RelayRouter__Internal__DeclarationsSupport.RouteRenderer.t<Internal.params, 'prepared>
diff --git a/examples/express/src/routes/__generated__/Route__Root__Todos__Single_route.res b/examples/express/src/routes/__generated__/Route__Root__Todos__Single_route.res
index 4ad6c7a..e9bc4f7 100644
--- a/examples/express/src/routes/__generated__/Route__Root__Todos__Single_route.res
+++ b/examples/express/src/routes/__generated__/Route__Root__Todos__Single_route.res
@@ -2,42 +2,28 @@
 // This file is autogenerated from `todoRoutes.json`, do not edit manually.
 module Internal = {
   @live
-  type prepareProps = {
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
+  type params = {
     todoId: string,
     statuses: option<array<TodoStatus.t>>,
     showMore: option<bool>,
   }
 
   @live
-  type renderProps<'prepared> = {
-    childRoutes: React.element,
-    prepared: 'prepared,
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
-    todoId: string,
-    statuses: option<array<TodoStatus.t>>,
-    showMore: option<bool>,
-  }
+  type prepareProps = RelayRouter__Internal__DeclarationsSupport.prepareProps<params>
 
-  @live
-  type renderers<'prepared> = {
-    prepare: prepareProps => 'prepared,
-    prepareCode: option<(. prepareProps) => array<RelayRouter.Types.preloadAsset>>,
-    render: renderProps<'prepared> => React.element,
-  }
   @live
   let makePrepareProps = (. 
     ~environment: RescriptRelay.Environment.t,
     ~pathParams: Js.Dict.t<string>,
     ~queryParams: RelayRouter.Bindings.QueryParams.t,
     ~location: RelayRouter.History.location,
-  ): prepareProps => {
+  ): prepareProps  => {
     {
       environment: environment,
   
       location: location,
+  
+      params: {
       todoId: pathParams->Js.Dict.unsafeGet("todoId"),
       statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
       showMore: queryParams->RelayRouter.Bindings.QueryParams.getParamByKey("showMore")->Belt.Option.flatMap(value => switch value {
@@ -47,6 +33,7 @@ module Internal = {
         }),
     }
   }
+  }
 
 }
 
@@ -194,9 +181,4 @@ let useIsRouteActive = (~exact=false) => {
   React.useMemo2(() => location->isRouteActive(~exact), (location, exact))
 }
 
-@obj
-external makeRenderer: (
-  ~prepare: Internal.prepareProps => 'prepared,
-  ~prepareCode: Internal.prepareProps => array<RelayRouter.Types.preloadAsset>=?,
-  ~render: Internal.renderProps<'prepared> => React.element,
-) => Internal.renderers<'prepared> = ""
\ No newline at end of file
+  type routeRenderer<'prepared> = RelayRouter__Internal__DeclarationsSupport.RouteRenderer.t<Internal.params, 'prepared>
diff --git a/examples/express/src/routes/__generated__/Route__Root__Todos_route.res b/examples/express/src/routes/__generated__/Route__Root__Todos_route.res
index 69c2246..6043019 100644
--- a/examples/express/src/routes/__generated__/Route__Root__Todos_route.res
+++ b/examples/express/src/routes/__generated__/Route__Root__Todos_route.res
@@ -2,42 +2,31 @@
 // This file is autogenerated from `todoRoutes.json`, do not edit manually.
 module Internal = {
   @live
-  type prepareProps = {
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
+  type params = {
     statuses: option<array<TodoStatus.t>>,
   }
 
   @live
-  type renderProps<'prepared> = {
-    childRoutes: React.element,
-    prepared: 'prepared,
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
-    statuses: option<array<TodoStatus.t>>,
-  }
+  type prepareProps = RelayRouter__Internal__DeclarationsSupport.prepareProps<params>
 
-  @live
-  type renderers<'prepared> = {
-    prepare: prepareProps => 'prepared,
-    prepareCode: option<(. prepareProps) => array<RelayRouter.Types.preloadAsset>>,
-    render: renderProps<'prepared> => React.element,
-  }
   @live
   let makePrepareProps = (. 
     ~environment: RescriptRelay.Environment.t,
     ~pathParams: Js.Dict.t<string>,
     ~queryParams: RelayRouter.Bindings.QueryParams.t,
     ~location: RelayRouter.History.location,
-  ): prepareProps => {
+  ): prepareProps  => {
     ignore(pathParams)
     {
       environment: environment,
   
       location: location,
+  
+      params: {
       statuses: queryParams->RelayRouter.Bindings.QueryParams.getArrayParamByKey("statuses")->Belt.Option.map(value => value->Belt.Array.keepMap(value => value->Js.Global.decodeURIComponent->TodoStatus.parse)),
     }
   }
+  }
 
 }
 
@@ -192,9 +181,4 @@ let useActiveSubRoute = (): option<[#ByStatus | #Single]> => {
   }, [location])
 }
 
-@obj
-external makeRenderer: (
-  ~prepare: Internal.prepareProps => 'prepared,
-  ~prepareCode: Internal.prepareProps => array<RelayRouter.Types.preloadAsset>=?,
-  ~render: Internal.renderProps<'prepared> => React.element,
-) => Internal.renderers<'prepared> = ""
\ No newline at end of file
+  type routeRenderer<'prepared> = RelayRouter__Internal__DeclarationsSupport.RouteRenderer.t<Internal.params, 'prepared>
diff --git a/examples/express/src/routes/__generated__/Route__Root_route.res b/examples/express/src/routes/__generated__/Route__Root_route.res
index c069fa0..4d5247e 100644
--- a/examples/express/src/routes/__generated__/Route__Root_route.res
+++ b/examples/express/src/routes/__generated__/Route__Root_route.res
@@ -2,40 +2,30 @@
 // This file is autogenerated from `routes.json`, do not edit manually.
 module Internal = {
   @live
-  type prepareProps = {
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
+  type params = {
   }
 
   @live
-  type renderProps<'prepared> = {
-    childRoutes: React.element,
-    prepared: 'prepared,
-    environment: RescriptRelay.Environment.t,
-    location: RelayRouter.History.location,
-  }
+  type prepareProps = RelayRouter__Internal__DeclarationsSupport.prepareProps<params>
 
-  @live
-  type renderers<'prepared> = {
-    prepare: prepareProps => 'prepared,
-    prepareCode: option<(. prepareProps) => array<RelayRouter.Types.preloadAsset>>,
-    render: renderProps<'prepared> => React.element,
-  }
   @live
   let makePrepareProps = (. 
     ~environment: RescriptRelay.Environment.t,
     ~pathParams: Js.Dict.t<string>,
     ~queryParams: RelayRouter.Bindings.QueryParams.t,
     ~location: RelayRouter.History.location,
-  ): prepareProps => {
+  ): prepareProps  => {
     ignore(pathParams)
     ignore(queryParams)
     {
       environment: environment,
   
       location: location,
+  
+      params: {
     }
   }
+  }
 
 }
 
@@ -80,9 +70,4 @@ let useActiveSubRoute = (): option<[#Todos]> => {
   }, [location])
 }
 
-@obj
-external makeRenderer: (
-  ~prepare: Internal.prepareProps => 'prepared,
-  ~prepareCode: Internal.prepareProps => array<RelayRouter.Types.preloadAsset>=?,
-  ~render: Internal.renderProps<'prepared> => React.element,
-) => Internal.renderers<'prepared> = ""
\ No newline at end of file
+  type routeRenderer<'prepared> = RelayRouter__Internal__DeclarationsSupport.RouteRenderer.t<Internal.params, 'prepared>
diff --git a/packages/rescript-relay-router/cli/RescriptRelayRouterCli__Codegen.res b/packages/rescript-relay-router/cli/RescriptRelayRouterCli__Codegen.res
index f6ec28e..3e0e9a6 100644
--- a/packages/rescript-relay-router/cli/RescriptRelayRouterCli__Codegen.res
+++ b/packages/rescript-relay-router/cli/RescriptRelayRouterCli__Codegen.res
@@ -328,8 +328,7 @@ let getRouteParamRecordFields = (route: printableRoute) => {
     ))
   })
 
-  let recordFields =
-    standardRecordFields->Array.concatMany([pathParamsRecordFields, queryParamsRecordFields])
+  let recordFields = Array.concat(pathParamsRecordFields, queryParamsRecordFields)
 
   {
     pathParamsRecordFields,
@@ -349,12 +348,17 @@ let getMakePrepareProps = (route: printableRoute, ~returnMode) => {
   let hasQueryParams = route.queryParams->Dict.keysToArray->Array.length > 0
   let params = route.params
 
-  let str = ref(`(. 
+  let str = ref(
+    `(. 
   ~environment: RescriptRelay.Environment.t,
   ~pathParams: Js.Dict.t<string>,
   ~queryParams: RelayRouter.Bindings.QueryParams.t,
   ~location: RelayRouter.History.location,
-): prepareProps => {\n`)
+)${switch returnMode {
+      | ForInlinedRouteFn => ""
+      | ForDedicatedRouteFile => ": prepareProps"
+      }}  => {\n`,
+  )
 
   let propsToIgnore = [
     params->Array.length === 0 ? Some("pathParams") : None,
@@ -378,8 +382,8 @@ let getMakePrepareProps = (route: printableRoute, ~returnMode) => {
   str.contents =
     str.contents ++ "  {
     environment: environment,\n
-    location: location,\n"
-
+    location: location,\n
+    params: {\n"
   params->Array.forEach(param => {
     str.contents =
       str.contents ++
@@ -407,7 +411,7 @@ let getMakePrepareProps = (route: printableRoute, ~returnMode) => {
     })
   }
 
-  str.contents = str.contents ++ "  }\n"
+  str.contents = str.contents ++ "  }\n}\n"
 
   if returnMode == ForInlinedRouteFn {
     str.contents = str.contents ++ `  prepareProps->unsafe_toPrepareProps\n`
@@ -455,7 +459,7 @@ ${queryParamsRecordFields
 }
 
 let getPrepareTypeDefinitions = (route: printableRoute) => {
-  let str = ref(`  @live\n  type prepareProps = {\n`)
+  let str = ref(`  @live\n  type params = {\n`)
 
   let {allRecordFields: recordFields} = getRouteParamRecordFields(route)
 
@@ -466,23 +470,7 @@ let getPrepareTypeDefinitions = (route: printableRoute) => {
   str.contents = str.contents ++ "  }\n\n"
 
   str.contents =
-    str.contents ++ `  @live\n  type renderProps<'prepared> = {
-    childRoutes: React.element,
-    prepared: 'prepared,\n`
-
-  recordFields->Array.forEach(((key, typ)) => {
-    str.contents = str.contents ++ `    ${key}: ${typ},\n`
-  })
-
-  str.contents = str.contents ++ "  }\n\n"
-
-  str.contents =
-    str.contents ++ `  @live\n  type renderers<'prepared> = {
-    prepare: prepareProps => 'prepared,
-    prepareCode: option<(. prepareProps) => array<RelayRouter.Types.preloadAsset>>,
-    render: renderProps<'prepared> => React.element,
-  }
-`
+    str.contents ++ "  @live\n  type prepareProps = RelayRouter__Internal__DeclarationsSupport.prepareProps<params>\n\n"
 
   str.contents =
     str.contents ++
@@ -501,12 +489,7 @@ let getPrepareAssets = () => {
   let str = ref("")
 
   str.contents =
-    str.contents ++ `@obj
-external makeRenderer: (
-  ~prepare: Internal.prepareProps => 'prepared,
-  ~prepareCode: Internal.prepareProps => array<RelayRouter.Types.preloadAsset>=?,
-  ~render: Internal.renderProps<'prepared> => React.element,
-) => Internal.renderers<'prepared> = ""`
+    str.contents ++ "  type routeRenderer<'prepared> = RelayRouter__Internal__DeclarationsSupport.RouteRenderer.t<Internal.params, 'prepared>\n"
 
   str.contents
 }
@@ -520,7 +503,7 @@ let rec getRouteDefinition = (route: printableRoute, ~indentation): string => {
 
   let str = `{
   let routeName = "${routeName}"
-  let loadRouteRenderer = () => (() => Js.import(${routeName}_route_renderer.renderer))->Obj.magic->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
+  let loadRouteRenderer = () => (() => Js.import(${routeName}_route_renderer.renderer))->doLoadRouteRenderer(~routeName, ~loadedRouteRenderers)
   let makePrepareProps = ${route->getMakePrepareProps(~returnMode=ForInlinedRouteFn)}
 
   {
diff --git a/packages/rescript-relay-router/cli/RescriptRelayRouterCli__Commands.res b/packages/rescript-relay-router/cli/RescriptRelayRouterCli__Commands.res
index c11c7d7..94de65d 100644
--- a/packages/rescript-relay-router/cli/RescriptRelayRouterCli__Commands.res
+++ b/packages/rescript-relay-router/cli/RescriptRelayRouterCli__Commands.res
@@ -44,15 +44,14 @@ let scaffoldRouteRenderers = (~deleteRemoved, ~config) => {
 
       Fs.writeFileIfChanged(
         Utils.pathInRoutesFolder(~config, ~fileName=Utils.toRendererFileName(routeName)),
-        `let renderer = Routes.${route.name->Types.RouteName.getFullRouteAccessPath}.makeRenderer(
-  ~prepare=props => {
+        `let renderer: Routes.${route.name->Types.RouteName.getFullRouteAccessPath}.routeRenderer<'prepared> = {
+  prepare: props => {
     ()
   },
-  ~render=props => {
+  render: props => {
     React.null
   },
-  (),
-)`,
+}`,
       )
 
       Console.log("Added \"" ++ Utils.toRendererFileName(routeName) ++ "\"")
@@ -135,8 +134,6 @@ let generateRoutes = (~scaffoldAfter, ~deleteRemoved, ~config) => {
   let fileContents = `
 open RelayRouter__Internal__DeclarationsSupport
 
-external unsafe_toPrepareProps: 'any => prepareProps = "%identity"
-
 let loadedRouteRenderers: Belt.HashMap.String.t<loadedRouteRenderer> = Belt.HashMap.String.make(
   ~hintSize=${routeNamesEntries->Array.length->Int.toString},
 )
diff --git a/packages/rescript-relay-router/src/RelayRouter__Internal__DeclarationsSupport.res b/packages/rescript-relay-router/src/RelayRouter__Internal__DeclarationsSupport.res
index de2dc55..7b2efe4 100644
--- a/packages/rescript-relay-router/src/RelayRouter__Internal__DeclarationsSupport.res
+++ b/packages/rescript-relay-router/src/RelayRouter__Internal__DeclarationsSupport.res
@@ -2,33 +2,39 @@
 
 exception Route_loading_failed(string)
 
-type prepareProps
-type prepared
-type renderProps
-
-//  This works because the render props for a route is always the prepared props
-//  + prepared + childRoutes. If that changes, this will also need to change
-//  accordingly.
-@val
-external unsafe_createRenderProps: (
-  {"prepared": prepared},
-  {"childRoutes": React.element},
-  prepareProps,
-) => renderProps = "Object.assign"
+type prepareProps<'params> = {
+  environment: RescriptRelay.Environment.t,
+  location: RelayRouter.History.location,
+  params: 'params,
+}
+
+type renderProps<'params, 'prepared> = {
+  childRoutes: React.element,
+  prepared: 'prepared,
+  environment: RescriptRelay.Environment.t,
+  location: RelayRouter.History.location,
+  params: 'params,
+}
 
 module RouteRenderer = {
-  type t = {
-    prepareCode: option<prepareProps => array<RelayRouter__Types.preloadAsset>>,
-    prepare: prepareProps => prepared,
-    render: renderProps => React.element,
+  type t<'params, 'prepared> = {
+    prepare: prepareProps<'params> => 'prepared,
+    prepareCode?: prepareProps<'params> => array<RelayRouter.Types.preloadAsset>,
+    render: renderProps<'params, 'prepared> => React.element,
   }
 }
 
+@unboxed type rec routeRenderer = RouteRenderer(RouteRenderer.t<'params, 'prepared>): routeRenderer
+
+type opaquePrepareProps
+
+external unsafe_toPrepareProps: prepareProps<'a> => prepareProps<'b> = "%identity"
+
 // This holder makes it easy to suspend (throwing the promise) or synchronously
 // return the loaded thing once availabile.
 type suspenseEnabledHolder<'thing> = NotInitiated | Pending(promise<'thing>) | Loaded('thing)
 
-type loadedRouteRenderer = suspenseEnabledHolder<RouteRenderer.t>
+type loadedRouteRenderer = suspenseEnabledHolder<routeRenderer>
 
 // This holds meta data for a route that has been prepared.
 type preparedContainer = {
@@ -37,19 +43,19 @@ type preparedContainer = {
   mutable timeout: option<Js.Global.timeoutId>,
 }
 
-type makePrepareProps = (
+type makePrepareProps<'params> = (
   ~environment: RescriptRelay.Environment.t,
   ~pathParams: Js.Dict.t<string>,
   ~queryParams: RelayRouter.Bindings.QueryParams.t,
   ~location: RelayRouter__History.location,
-) => prepareProps
+) => prepareProps<'params>
 
 let doLoadRouteRenderer = (
-  loadFn: unit => promise<RouteRenderer.t>,
+  loadFn: unit => promise<RouteRenderer.t<'params, 'prepared>>,
   ~routeName,
-  ~loadedRouteRenderers,
+  ~loadedRouteRenderers: Belt.HashMap.String.t<loadedRouteRenderer>,
 ) => {
-  let promise = loadFn()
+  let promise = loadFn()->Promise.thenResolve(p => RouteRenderer(p))
   loadedRouteRenderers->Belt.HashMap.String.set(routeName, Pending(promise))
 
   promise->(Js.Promise.then_(routeRenderer => {
@@ -58,10 +64,13 @@ let doLoadRouteRenderer = (
     }, _))
 }
 
+external opaqueRouteRenderer: RouteRenderer.t<'a, 'b> => RouteRenderer.t<'c, 'd> = "%identity"
+let unwrapRouteRenderer = (RouteRenderer(routeRenderer)) => opaqueRouteRenderer(routeRenderer)
+
 // This does a bunch of suspense/React gymnastics for kicking off code
 // preloading for a matched route..
 let preloadCode = (
-  ~loadedRouteRenderers,
+  ~loadedRouteRenderers: Belt.HashMap.String.t<loadedRouteRenderer>,
   ~routeName,
   ~loadRouteRenderer,
   ~makePrepareProps,
@@ -70,10 +79,10 @@ let preloadCode = (
   ~queryParams,
   ~location,
 ) => {
-  let apply = (routeRenderer: RouteRenderer.t) => {
+  let apply = (routeRenderer: routeRenderer) => {
     let preparedProps = makePrepareProps(~environment, ~pathParams, ~queryParams, ~location)
 
-    switch routeRenderer.prepareCode {
+    switch unwrapRouteRenderer(routeRenderer).prepareCode {
     | Some(prepareCode) => prepareCode(preparedProps)
     | None => []
     }
@@ -101,7 +110,7 @@ let preloadCode = (
   }
 }
 
-type prepareAssets = {
+type prepareAssets<'params> = {
   getPrepared: (~routeKey: Belt.HashMap.String.key) => option<preparedContainer>,
   prepareRoute: (
     ~environment: RescriptRelay.Environment.t,
@@ -113,7 +122,7 @@ type prepareAssets = {
       ~pathParams: Js.Dict.t<string>,
       ~queryParams: RelayRouter.Bindings.QueryParams.t,
       ~location: RelayRouter__History.location,
-    ) => prepareProps,
+    ) => prepareProps<'params>,
     ~makeRouteKey: (
       ~pathParams: Js.Dict.t<string>,
       ~queryParams: RelayRouter.Bindings.QueryParams.t,
@@ -126,7 +135,10 @@ type prepareAssets = {
 }
 
 // Creates the assets needed for preparing routes.
-let makePrepareAssets = (~loadedRouteRenderers, ~prepareDisposeTimeout): prepareAssets => {
+let makePrepareAssets = (
+  ~loadedRouteRenderers: Belt.HashMap.String.t<loadedRouteRenderer>,
+  ~prepareDisposeTimeout,
+): prepareAssets<'params> => {
   let preparedMap: Belt.HashMap.String.t<preparedContainer> = Belt.HashMap.String.make(~hintSize=3)
 
   let getPrepared = (~routeKey) => preparedMap->Belt.HashMap.String.get(routeKey)
@@ -226,7 +238,7 @@ let makePrepareAssets = (~loadedRouteRenderers, ~prepareDisposeTimeout): prepare
       ~pathParams: Js.Dict.t<string>,
       ~queryParams: RelayRouter.Bindings.QueryParams.t,
       ~location: RelayRouter__History.location,
-    ) => prepareProps,
+    ) => prepareProps<'params>,
     ~makeRouteKey: (
       ~pathParams: Js.Dict.t<string>,
       ~queryParams: RelayRouter.Bindings.QueryParams.t,
@@ -267,9 +279,10 @@ let makePrepareAssets = (~loadedRouteRenderers, ~prepareDisposeTimeout): prepare
     | (Some(_), Render)
     | // Same goes if we had no previous prepare, do a fresh instantiation.
     (None, _) =>
-      let preparedRef: ref<suspenseEnabledHolder<prepared>> = ref(NotInitiated)
+      let preparedRef: ref<suspenseEnabledHolder<'prepared>> = ref(NotInitiated)
 
-      let doPrepare = (routeRenderer: RouteRenderer.t) => {
+      let doPrepare = routeRenderer => {
+        let routeRenderer = unwrapRouteRenderer(routeRenderer)
         switch routeRenderer.prepareCode {
         | Some(prepareCode) =>
           let _ = prepareCode(preparedProps)
@@ -342,13 +355,14 @@ let makePrepareAssets = (~loadedRouteRenderers, ~prepareDisposeTimeout): prepare
           suspend(promise)
           React.null
         | (Some(Loaded(routeRenderer)), Loaded(prepared)) =>
-          routeRenderer.render(
-            unsafe_createRenderProps(
-              {"prepared": prepared},
-              {"childRoutes": childRoutes},
-              preparedProps,
-            ),
-          )
+          let routeRenderer = unwrapRouteRenderer(routeRenderer)
+          routeRenderer.render({
+            childRoutes,
+            prepared,
+            environment: preparedProps.environment,
+            location: preparedProps.location,
+            params: preparedProps.params,
+          })
         | _ =>
           Js.log("Warning: Invalid state")
           React.null
diff --git a/packages/rescript-relay-router/src/RelayRouter__Internal__DeclarationsSupport.resi b/packages/rescript-relay-router/src/RelayRouter__Internal__DeclarationsSupport.resi
index 95d7552..20ad6c1 100644
--- a/packages/rescript-relay-router/src/RelayRouter__Internal__DeclarationsSupport.resi
+++ b/packages/rescript-relay-router/src/RelayRouter__Internal__DeclarationsSupport.resi
@@ -1,12 +1,34 @@
-type prepareProps
+type prepareProps<'params> = {
+  environment: RescriptRelay.Environment.t,
+  location: RelayRouter.History.location,
+  params: 'params,
+}
+
+type renderProps<'params, 'prepared> = {
+  childRoutes: React.element,
+  prepared: 'prepared,
+  environment: RescriptRelay.Environment.t,
+  location: RelayRouter.History.location,
+  params: 'params,
+}
 
 module RouteRenderer: {
-  type t
+  type t<'params, 'prepared> = {
+    prepare: prepareProps<'params> => 'prepared,
+    prepareCode?: prepareProps<'params> => array<RelayRouter.Types.preloadAsset>,
+    render: renderProps<'params, 'prepared> => React.element,
+  }
 }
 
+@unboxed type rec routeRenderer = RouteRenderer(RouteRenderer.t<'params, 'prepared>): routeRenderer
+
+type opaquePrepareProps
+
+external unsafe_toPrepareProps: prepareProps<'a> => prepareProps<'b> = "%identity"
+
 type suspenseEnabledHolder<'thing> = NotInitiated | Pending(promise<'thing>) | Loaded('thing)
 
-type loadedRouteRenderer = suspenseEnabledHolder<RouteRenderer.t>
+type loadedRouteRenderer = suspenseEnabledHolder<routeRenderer>
 
 type preparedContainer = {
   disposables: array<unit => unit>,
@@ -14,31 +36,31 @@ type preparedContainer = {
   mutable timeout: option<Js.Global.timeoutId>,
 }
 
-type makePrepareProps = (
+type makePrepareProps<'params> = (
   ~environment: RescriptRelay.Environment.t,
   ~pathParams: Js.Dict.t<string>,
   ~queryParams: RelayRouter.Bindings.QueryParams.t,
   ~location: RelayRouter__History.location,
-) => prepareProps
+) => prepareProps<'params>
 
 let doLoadRouteRenderer: (
-  unit => promise<RouteRenderer.t>,
+  unit => promise<RouteRenderer.t<'params, 'prepared>>,
   ~routeName: Belt.HashMap.String.key,
-  ~loadedRouteRenderers: Belt.HashMap.String.t<suspenseEnabledHolder<RouteRenderer.t>>,
+  ~loadedRouteRenderers: Belt.HashMap.String.t<loadedRouteRenderer>,
 ) => promise<unit>
 
 let preloadCode: (
-  ~loadedRouteRenderers: Belt.HashMap.String.t<suspenseEnabledHolder<RouteRenderer.t>>,
+  ~loadedRouteRenderers: Belt.HashMap.String.t<loadedRouteRenderer>,
   ~routeName: Belt.HashMap.String.key,
   ~loadRouteRenderer: unit => promise<unit>,
-  ~makePrepareProps: makePrepareProps,
+  ~makePrepareProps: makePrepareProps<'params>,
   ~environment: RescriptRelay.Environment.t,
   ~pathParams: Js.Dict.t<string>,
   ~queryParams: RelayRouter.Bindings.QueryParams.t,
   ~location: RelayRouter__History.location,
 ) => promise<array<RelayRouter__Types.preloadAsset>>
 
-type prepareAssets = {
+type prepareAssets<'params> = {
   getPrepared: (~routeKey: Belt.HashMap.String.key) => option<preparedContainer>,
   prepareRoute: (
     ~environment: RescriptRelay.Environment.t,
@@ -50,7 +72,7 @@ type prepareAssets = {
       ~pathParams: Js.Dict.t<string>,
       ~queryParams: RelayRouter.Bindings.QueryParams.t,
       ~location: RelayRouter__History.location,
-    ) => prepareProps,
+    ) => prepareProps<'params>,
     ~makeRouteKey: (
       ~pathParams: Js.Dict.t<string>,
       ~queryParams: RelayRouter.Bindings.QueryParams.t,
@@ -63,6 +85,6 @@ type prepareAssets = {
 }
 
 let makePrepareAssets: (
-  ~loadedRouteRenderers: Belt.HashMap.String.t<suspenseEnabledHolder<RouteRenderer.t>>,
+  ~loadedRouteRenderers: Belt.HashMap.String.t<loadedRouteRenderer>,
   ~prepareDisposeTimeout: int,
-) => prepareAssets
+) => prepareAssets<'params>