[Python-Dev] Tail recursion

Christian Tismer tismer at tismer.com
Mon Nov 24 11:31:44 EST 2003

Guido van Rossum wrote:

>>>Tail Recursion

> AFAIK Stackless only curtails the *C* stack, not the chain of Python
> frames on the heap.


> But I have a problem with tail recursion.  It's generally requested by
> new converts from the Scheme/Lisp or functional programming world, and
> it usually means they haven't figured out yet how to write code
> without using recursion for everything yet.  IOW I'm doubtful on how
> much of a difference it would make for real Python programs (which,
> simplifying a bit, tend to use loops instead of recursion).  And also
> note that even if an exception is not caught, you'd like to see all
> stack frames listed when the traceback is printed or when the debugger
> is invoked.

Same here. I'm not for automatic tail recursion detection.
A very simple approach, also pretty easy to implement
would be a "jump" property, which would be added to a function.
It would simply allow to run a different (or the same) function than
the current one without returning.

def sort3(a, b, c):
   if a>b:
     return sort3.jump(b, a, c)
   if b>c:
     return sort3.jump(a, c, b)
   return a, b, c

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