2 files changed, 21 insertions, 0 deletions
diff --git a/src/Gtk/State.dcl b/src/Gtk/State.dcl
index 81373e2..e97f3d3 100644
--- a/src/Gtk/State.dcl
+++ b/src/Gtk/State.dcl
@@ -27,4 +27,7 @@ runGtk :: !(GtkM a) !*World -> (!a, !*World)
 toState :: !(A.a: a -> a) -> GtkM ()
 toStateR :: !(A.a: a -> (r,a)) -> GtkM r
 
+appWorld :: !(*World -> *World) -> GtkM ()
+accWorld :: !(*World -> (r,*World)) -> GtkM r
+
 quit :: GtkM ()
diff --git a/src/Gtk/State.icl b/src/Gtk/State.icl
index 9d81b9a..245ea7a 100644
--- a/src/Gtk/State.icl
+++ b/src/Gtk/State.icl
@@ -53,5 +53,23 @@ toState f = state \st -> let w = f st.world in ((), {st & world=w})
 toStateR :: !(A.a: a -> (r,a)) -> GtkM r
 toStateR f = state \st -> let (r,w) = f st.world in (r, {st & world=w})
 
+appWorld :: !(*World -> *World) -> GtkM ()
+appWorld f = state \st
+	# w = f (voidToWorld st.world)
+	-> ((), {st & world=worldToVoid w})
+
+accWorld :: !(*World -> (r,*World)) -> GtkM r
+accWorld f = state \st
+	# (r,w) = f (voidToWorld st.world)
+	-> (r, {st & world=worldToVoid w})
+
+voidToWorld :: !() -> *World
+voidToWorld _ = code {
+	no_op
+}
+
+worldToVoid :: !*World -> ()
+worldToVoid _ = ()
+
 quit :: GtkM ()
 quit = modify \st -> {st & return=True}