Sorry Nuance, Recursion is NOT a loop.
Recursion works by building up the stack,
delaying evaluation until the end.
A loop evaluates as it goes. There is a big difference
between the two. Think about it this way: The recursive
method that I posted says to add the first number to the
sum of the other numbers. That can't be done until the sum
of the other numbers is known, so it puts the number on the
stack and trys to sum the other numbers by the same method.
It does this, pushing the list onto a stack, until there is
only one number left, then it sums the stack. This is not a
loop. Its not even close.
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Some programming languages optomize tail-recursion down
to a loop (to prevent the procedure call/stack overhead).
So at least I would say that tail-recursion is a looping
construct (or at least very close to one). Also
some languages (ML, Prolog) have no
*standard* looping constructs (while, for, etc..) so
all looping in those languages is implemented with
recursion. So in at least those languages recursion
*is* a looping construct.
The call is harder to make in Perl, since I don't believe
it optomizes tail-recursion down to a loop, and it does
have normal looping operators. There are cases
where recursion is clearly not a looping construct,
but I must say that in
some instances recursion clearly is a looping construct.
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Well, I disagree with you here. And, so do the people I asked for opinions. Recursion is a looping construct. Even your explination is a loop. You can not push things onto a stack and then evaluate what is on that stack incrementally without a loop. No need to really continue this, but after trying to find anyone else I know to have the same opinion as you, I stand by everyone elses answers that this can't be done without looping, and that recursion is indeed a looping construct. Just take a pencil and paper and draw out a flow of the snippet you gave, you will see the obvious loop.
Cheers,
KM
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