Exercise 4.28 - why you need (actual-value (operator exp)) in eval. the first Exercise with a relatively trivial answer that downright stumped me...
Exercise 4.29 - memoization and performance of lazy evaluation. i don't really understand my own pathological example...
just fiddling with code (accidental commit)
TODO: why would the lack of memoization make a tail-recursive process slow down GRADUALLY???