Which should I use?
lDonŐt lose sleep over whether to tail-recurse, unless
lyou are processing large data
objects and memory is a premium, or
lit is much costlier to compute without it, or
litŐs stated on the exam that you should.
lThe compiler must also
optimize tail-recursion for this to be effective (currently rex doesnŐt).
lIn development, it might be
wise to provide the clearest expression
of the function first, then later replace it with a tail-recursive version.