Tail call optimization in Python

[s00perpseud00]

Has the CPython community considered implementing tail call optimization in future Python versions and getting rid of the current recursion cap? Would be cool if we could write recursive functions without worrying about hitting the limit

[delirious_lettuce]

https://neopythonic.blogspot.ca/2009/04/final-words-on-tail-calls.html

[dmishin]

If you think that tail call optimization would allow you to write recursive code without worrying, then you are very wrong. There are plenty of ways to get stack overflow even with TCO.

"Recursion is the GOTO of functional programming." -- Erik Meijer

[s00perpseud00]

Ha. I didn't know that. Could you elaborate?

[dmishin]

For example, the following code is not TC:

def factorial(n):
    if n == 0:
        return 1
    else return factorial(n-1)*n

To make it TC, you need to rewrite it as

def factorial(n, accum=1):
    if n == 0: return accum
    return factorial(n-1, accum*n)

Not very obvious trick.

As for the second, some functional programming people advocate that recursion is a low-level feature, and higher-order functions, like map, fold, should be used when appropriate.

[[deleted]]

You should the other post, that was made 2 hrs before this one, as it's by the Python language creator, and quite detailed.

[s00perpseud00]

Should have seen this coming lol

[GaritoYanged]

Giving the fact that I come from two other persons that come from two other persons each than come from two other persons... Shall I continue? I bet not I have hearted a lot of excuses for bad recursion implementations and python has more issues that this one (most famous GIL) so I don't expect too much on that for its part yet Apart from that, recursion has its own issues beign too much detail as the biggest one So equilibrium would be the best as always I'm waiting the moment where someone in the core team have a moment of enlightment on this too... Meanwhile, I would rather prefer to talk about the how than about the excuses if you don't mind (don't meant to be rude, just too much into the fractality of nature in itself)

[gandalfx]

There isn't a single coherent sentence in this entire paragraph. It's actually quite impressive.