On 2007-06-12, Anders J. Munch <[EMAIL PROTECTED]> wrote: > Paul Rubin wrote: >> Steven D'Aprano <[EMAIL PROTECTED]> writes: >>>> 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. >> >> The usual compiler method is to translate the code into >> continuation-passing style and thereby gain tail-recursion >> optimization automagically. > > There's no need to go into CPS just to optimise tail-recursion. > After all, compilers were optimising tail-calls decades before > Appel's work on SML/NJ. > > Converting tail-recursion to iteration is trivial, and > perfectly reasonable for a human to do by hand.
For simple recursive tail calls, yeah, it can be. Translating a tail-recursive Factorial function into a while loop is easy. But tail-call optimization technically works for any tail-call, including mutual recursion, and non-recursive tail-calls. You can't reasonably hand-optimize away the stack frame for all tail-calls. def foo(x) bar(x) The only way to hand-optimize the call to bar is to inline it yourself. -- Neil Cerutti Will the highways on the Internet become more few? --George W. Bush -- http://mail.python.org/mailman/listinfo/python-list
