This is such a key insight core to many of the benefits of FP. Other resources on the matter that I like include Meijer, E., Fokkinga, M., & Paterson, R. (1991

This is such a key insight core to many of the benefits of FP. Other resources on the matter that I like include Meijer, E., Fokkinga, M., & Paterson, R. (1991). Functional programming with bananas, lenses, envelopes and barbed wire, 124–144. Hutton, G. (1999). A tutorial on the universality and expressiveness of fold. Journal of Functional Programming, 9(4), 355–372. Gibbons, J., Hutton, G., & Altenkirch, T. (2001). When is a function a fold or an unfold? Electronic Notes in Theoretical Computer Science, 44(1), 146–160. (The third one is for theoretical interest mostly)