On Mon, 11 Jun 2007 01:28:09 +0100, Alexander Schmolck wrote: > Steven D'Aprano <[EMAIL PROTECTED]> writes: > >> On Sat, 09 Jun 2007 22:42:17 +0100, Alexander Schmolck wrote: >> >>>> As for why tail calls are not optimized out, it was decided that being able >>>> to have the stack traces (with variable information, etc.) was more useful >>>> than offering tail call optimization >>> >>> I don't buy this. >> >> Do you mean you don't believe the decision was made, or you don't agree >> with the decision? > > Neither. I don't believe the rationale stated in this thread to be the true > reason.
Don't keep us in suspense. What do you believe is the true reason? >> Are you volunteering? If you are, I'm sure your suggestion will be welcomed >> gratefully. > > I rather doubt it. Guido has stated quite clearly that his not > interested in incorporating this feature. He's not the only one who gets to make these decisions. But even if he uses his veto to prevent tail-recursion optimization from being put into the main branch, there are other options. >>>> (do what I say). >>> >>> Where did you say run out of memory and fail? More importantly how do >>> you say "don't run out of memory and fail"? >> >> If we can live with a certain amount of "arbitrary failures" in simple >> arithmetic, > > I prefer not too, and thus when possible avoid to use languages where > ``a + b`` is liable to fail arbitrarily (such as C, where the behavior > will often be undefined). That's not the sort of arbitrary failure I was discussing, but for that matter Python is one of those languages. Perhaps Python is not the language for you? Correct me if I'm wrong, but surely it is C++ that can have arbitrary behaviour for "a + b", not C? >> then the world won't end if tail recursion isn't optimized away by the >> compiler. > > I'd personally much rather have arithmetic working properly. > Unfortunately this is not an option at the moment, although quite a few > smart people are working on it and although it is an immensely costly > problem. > >> You can always hand-optimize it yourself. > > Not tail calls, in general, no. Sorry, how does that work? You're suggesting that there is an algorithm which the compiler could follow to optimize away tail-recursion, but human beings can't follow the same algorithm? Now I'm confused. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
