there is also the introductory article "Species and Functors and Types, Oh My!" which explores some of these ideas applied to examples from Haskell: http://158.

there is also the introductory article "Species and Functors and Types, Oh My!" which explores some of these ideas applied to examples from Haskell: http://158.130.69.163/~byorgey/pub/species-pearl.pdf http://158.130.69.163/~byorgey/pub/species-pearl.pdf