-- |
--
-- >>> fstL |= Just 3 $ (7, "abc")
-- Just (3,"abc")
--
-- >>> (fstL |= (+1) $ (3, "abc")) 17
-- (18,"abc")
(|=) ::
  Functor f =>
  Lens s t a b
  -> f b
  -> s
  -> f t
(|=) =
  error "todo: (|=)"
(|=) ::
  Functor f =>
  Lens s t a b
  -> f b
  -> s
  -> f t
(|=) =
  error "todo: (|=)"
(|=) =
  error "todo: (|=)"