It just occurred to me that...

If you are preparing a cucumber for a greek salad, that it DOES NOT MATTER if you cut the cumber radially ( into circles) and then cut those into quarters.

OR

If you cut the cucumber along it's long axis into quarters, and then chop those into smaller pieces.

And this is a real world application of Theorems for Free, Wadler 1989

https://people.mpi-sws.org/~dreyer/tor/papers/wadler.pdf