Here is a proof in Haskell: https://gist.github.com/946245 https://gist.github.com/946245 The function fib is abstracting away all the details of calculating t

Here is a proof in Haskell: https://gist.github.com/946245 https://gist.github.com/946245 The function fib is abstracting away all the details of calculating the nth member of the Fibonnaci Numbers. Sadly we are working with machines, not pure mathematical concepts - so when poor Bob will try to do something like [fib x| x <- [1..9999]] with the first implementation and will see his computer grinding to a halt he will have a leaky abstraction. Basically the law of leaky abstractions just says that if you don't know everything about the abstractions you use you will eventually get hit in the head by one of them.