Sat Jun 16 23:42:54 EDT 2018

Natural transformations


This has an interesting remark about natural transformations:

If F and G are functors, and h is a natural transformation h:F=>G,
then we have that

  h . fmap f = fmap f . h

If we think of F and G as containers, then this rule says that a
natural transformation relates the structures of the containers, not
the contents.