1 files changed, 9 insertions, 1 deletions
diff --git a/src/Language/Fiddle/Ast/Internal/Instances/Walk.hs b/src/Language/Fiddle/Ast/Internal/Instances/Walk.hs
index d80963d..221dd5b 100644
--- a/src/Language/Fiddle/Ast/Internal/Instances/Walk.hs
+++ b/src/Language/Fiddle/Ast/Internal/Instances/Walk.hs
@@ -1,8 +1,16 @@
-module Language.Fiddle.Ast.Internal.Instances.Walk (Walk (..), GWalk (..)) where
+module Language.Fiddle.Ast.Internal.Instances.Walk (Walk (..), GWalk (..), walk_) where
 
 import Data.Typeable
 import GHC.Generics
 
+-- | Like walk, but assumes no local state.
+walk_ ::
+  (Monad m, Traversable f, Typeable f, Typeable a, Walk t) =>
+  (forall t'. (Walk t', Typeable t', Typeable f, Typeable a) => t' f a -> m ()) ->
+  t f a ->
+  m ()
+walk_ fn t = walk (\t _ -> fn t) t ()
+
 class (Typeable t) => Walk t where
   walk ::
     (Monad m, Traversable f, Typeable f, Typeable a) =>