diff --git a/haskell/Main.hs b/haskell/Main.hs
index 69175d2..c61db06 100644
--- a/haskell/Main.hs
+++ b/haskell/Main.hs
@@ -41,7 +41,7 @@ main =
                     describe pt do
                         input <- liftIO $ parseFile $ "../inputs/" <> t <> "/" <> pt
                         let (rs, os) =
-                                ((getConst . foldHListF (\x r -> Const $ fst x : getConst r) (Const [])) &&& foldHListF (HCons . snd) HNil) $
+                                (foldHListF0 ((:) . fst) [] &&& foldHListF (HCons . snd) HNil) $
                                     mapHListF (\(Fanout (f, Op o)) -> (o &&& id) $ f input) parts
                         for_ (zip [1 :: Int ..] rs) $ uncurry $ \(show -> n) ->
                             it n . pureGoldenTextFile ("../outputs/" <> t <> "/" <> pt <> "/" <> n) . (<> "\n")
diff --git a/haskell/Pre.hs b/haskell/Pre.hs
index bbbf6c5..f087d17 100644
--- a/haskell/Pre.hs
+++ b/haskell/Pre.hs
@@ -43,6 +43,7 @@ module Pre (
     sortPair,
     HListF (..),
     foldHListF,
+    foldHListF0,
     mapHListF,
     (/\),
     (/\\),
@@ -150,6 +151,10 @@ foldHListF :: (forall x xs. f x -> r xs -> r (x ': xs)) -> r '[] -> HListF f as
 foldHListF f e = \case
     HNilF -> e
     HConsF x xs -> f x $ foldHListF f e xs
+foldHListF0 :: (forall x. f x -> r -> r) -> r -> HListF f as -> r
+foldHListF0 f e = \case
+    HNilF -> e
+    HConsF x xs -> f x $ foldHListF0 f e xs
 mapHListF :: (forall a. f a -> g a) -> HListF f as -> HListF g as
 mapHListF t = foldHListF (\x r -> HConsF (t x) $ r) HNilF