Does Python Perform Tail Recursion Optimization?

Tail Recursion Optimization in Python

Python does not optimize tail recursion, as confirmed by Guido van Rossum's explicit decision not to implement it due to the preservation of proper tracebacks.

Question: Is Python capable of tail recursion optimization?

Answer: No.

Discussion:

To illustrate the issue, consider the following Python code that calculates the sum of a triangular series:

def trisum(n, csum):
    if n == 0:
        return csum
    else:
        return trisum(n - 1, csum + n)

When executed with a large value for n, this code fails due to excessive recursion depth. Tail recursion optimization could alleviate this issue by replacing the recursive call with a jump to the beginning of the function with updated parameters.

However, Python does not implement tail recursion optimization because Guido van Rossum prioritized maintaining proper tracebacks.

Optimization Workaround:

If tail recursion optimization is desired, Python code can be manually transformed to eliminate recursion. Here is a modified version of the trisum function:

def trisum(n, csum):
    while True:                     # Change recursion to a while loop
        if n == 0:
            return csum
        n, csum = n - 1, csum + n   # Update parameters instead of tail recursion

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