fmap-fmap-fmap https://twitter.com/Iceland_jack/status/1176667991351726087

fmap-fmap-fmap.hs

fmap . fmap . fmap
  :: (Functor f1, Functor f2, Functor f3) =>
     (a -> b) -> f1 (f2 (f3 a)) -> f1 (f2 (f3 b))

fmap . fmap . fmap
== fmap . (fmap . fmap)
== fmap . (fmap fmap fmap)
== fmap fmap (fmap fmap fmap)
== (fmap fmap . fmap fmap) fmap
== fmap (fmap fmap) (fmap fmap) fmap
== ((fmap . fmap) fmap) (fmap fmap) fmap
== (fmap fmap fmap fmap) (fmap fmap) fmap
== ((fmap fmap fmap fmap . fmap) fmap) fmap
== ((fmap fmap fmap fmap fmap fmap) fmap) fmap
== fmap fmap fmap fmap fmap fmap fmap fmap