factorial

Okay but if you are going to call the function factorial, why not have it actually calculate a factorial?

Erlang does it very much like GP's suggestion with the one downside of being 'noisy' with its punctuation (some might say 'clearer'): factorial(0) -> 1; factorial(N) -> N * factorial(N-1).

The negative factorial issue arises from a slightly awkward specification of the set, not from jameshart's core idea.

If this API changed to an exponential or factorial running time, almost all users of it would be completely broken.

So HOL4 will try to determine whether you're using mosml or polyml by calculating factorial 100.

Would be much more compelling to me than the factorial demo you've written up so far.

And if you extend it, it's not the factorial function anymore, which is defined to have the non-negative integers as its domain.

Example of anonymous recursive function with arguments.callee: var factorial=function(n) { return (!(n>1))?

However, you can see in the demos page some classical computation problems: Ackermann function, factorial, predecessor.

This would have done the job: def factorial(N, result=1): if N == 1: return result return factorial(N-1, N*result) Assuming that you never call it with the result argument.

My intuition is telling me that the naive implementation its factorial time due to the problem of selecting combinations of users and posts to test.

Then you start playing with it (as this paper did), you create a hello world program, you solve the factorial function recursively, and so on.

Yes, I read the entire article, maybe I didn't articulate correctly, my point is, given you are in an interview and somebody asks you "Show me factorial please", wouldn't be a smarter move to import a module that something already wrote and just use it?