On Sep 22, 7:13 pm, process <[EMAIL PROTECTED]> wrote: > Why doesn't Python optimize tailcalls? Are there plans for it? > > I know GvR dislikes some of the functional additions like reduce and > Python is supposedly about "one preferrable way of doing things" but > not being able to use recursion properly is just a big pain in the > a**.
Eliminating tail calls affects the semantics of your program (by changing memory complexity). As an optimization, it's a side-effect of the implementation, which is a particularly nasty kind of side- effect. Even if guaranteed it's fairly subtle. "return x()" would be optimized while "return x() + 1" would not. Or maybe you're calling a function that uses a wrapper and the wrapper isn't tweaked right to be optimized. Recursion in general can be very useful, but not tail-recursion. The only time it's not trivial to convert tail-recursion into a loop is when it involves multiple functions, but even that can be done if you know how. -- http://mail.python.org/mailman/listinfo/python-list
