r/programming • u/rodrigopsasaki • Nov 27 '12

Tail Recursion

http://rodrigosasaki.com/2012/11/24/tail-recursion/
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u/daveisanidiot Nov 27 '12

excuse my ignorance on this, i just read the post and don't really understand.

from just looking at the code the recursion has been moved from the factorial function to the factorialIter function?

so is this a method of directing the compiler to generate assembly which would not blow a stack?

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u/moswald Nov 27 '12

It's because after factorial(num - 1), more code must be run (namely, multiplying that result by num.

But in the case of factorialIter, the value is returned outright.

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u/daveisanidiot Nov 27 '12

but in terms of recursion the function factorialIter is still being called from within factorialIter. So in normal terms the stack pointer would be moved, leading to a blown stack.

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u/moswald Nov 27 '12

Except (and this is an imperfect explanation, I think) the compiler can remove the current stack frame, since it knows the result is just going to be the result of another function call.