Current example: I'm currently reading Programming in Scala, the bible of the language. (Not the formal spec, but essentially the K&R equivalent -- well worth buying an e-copy and reading, if you're into programming languages. It's a dense but remarkably neat language, and wonderfully pragmatic.)
Anyway, section 8.9 describes Scala's limited but decently powerful tail-recursion capabilities. And the very last paragraph, after several pages, says,
Thus, tail-call optimization is limited to situations in which a method or nested function calls itself directly as its last operation, without going through a function value or some other intermediary. (If you don’t fully understand tail recursion yet, see Section 8.9).Which may be the best way I've ever seen to underscore the point...
