Not OP but they meant https://hackage.haskell.org/package/base-4.16.1.0/docs/Data-...

As you have the normal map function for Functors (using Haskell):

  > :t fmap
  fmap :: Functor f => (a -> b) -> f a -> f b

you can have bimap for Bifunctors:

  > :t bimap
  bimap :: Bifunctor p => (a -> b) -> (c -> d) -> p a c -> p b d

which specialised to pairs is:

  > :t bimap @(,)
  bimap @(,) :: (a -> b) -> (c -> d) -> (a, c) -> (b, d)