[Haskell-beginners] Applicability of FP unchanging things to real world changing things

[Isaac Dupree]

Computers think discretely.  Even the OO book is probably not going to 
recognize the book's every move as it falls into someone's hands, 
wanders around the library, perhaps sneaks out of the library or is 
reshelved somewhere else, is checked out and goes across the globe, has 
the cover torn and then taped together into pretty-good shape...

I prefer FP because it acknowledges that computers fundamentally operate 
  like this. They model and approximate situations.  Sometimes 
pretending to be those situations is not the best way to approximate them.

...[tried to give example but I'm too dizzy at the moment from finals-week]