Is tail recursion supported by Numba?

Numba Development
1

Is tail recursion supported by Numba? I.e., do I have to rewrite recursive functions in a loop style to get the best performance?

2

Interesting question! Below are code and timings via Jupyter %timeit to examine. The code is straight from Tail Recursion - GeeksforGeeks.

Tail Recursive Factorial

from numba import njit

@njit
def fact_tailrecursive(n, a = 1):
 
    if (n == 0):
        return a
 
    return fact_tailrecursive(n - 1, n * a)

232 ns ± 3.6 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

Loop Factorial

@njit
def fact_loop(n):

    a = 1

    for i in range(n):
        a *= (i + 1)

    return(a)

157 ns ± 0.996 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

Inbuilt Factorial (Gamma)

import math

@njit
def fact_gamma(n):
    return math.gamma(n + 1)

169 ns ± 0.644 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

Hopefully that answers your question.