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data ConsnoC a = Nil
               | Cons a (ConsnoC a)
               | Snoc (ConsnoC a) a

foldlC :: (a -> b -> a) -> a -> ConsnoC b -> a
foldlC f u Nil         = u
foldlC f u (Cons x xs) = foldlC f (f u x) xs
foldlC f u (Snoc xs x) = f (foldlC f u xs) x

foldrC :: (a -> b -> b) -> b -> ConsnoC a -> b
foldrC f u xs = go xs u
  where
    go Nil         = id
    go (Cons x xs) = f x . go xs
    go (Snoc xs x) = go xs . f x