Project Euler Problem 1 functionally

I'm trying to learn a bit of elisp (see Luhns Algorithm in elisp). So, to try out me elisp some more I tried the Project Euler's simplest problem, Problem 1. So, I cracked open emacs and tried out a few things, gave up and went into hibernation. A few weeks later I remembered this problem and had a go at it again. I thought I nailed it...

	(defun num_check (x) (if (or (eq (mod x 3) 0) (eq (mod x 5) 0)) x 0))
	(defun sum(x) (if (eq x 3) 3 (+ (num_check x) (sum (- x 1)))))
	(sum 3)
	3
	(sum 5)
	8
	(sum 10)
	33
	(sum 1000)
	Debugger entered--Lisp error: (error "Lisp nesting exceeds `max-lisp-eval-depth'")

view raw luhn.el hosted with ❤ by GitHub

After a bit of googling I found out the elisp only supports 300 recursive calls :(. So, I decided to take the plunge into clisp and started downloading that. Meanwhile I had some old version of scala available and tried this

	Welcome to Scala version 2.9.0.1 (Java HotSpot(TM) Server VM, Java 1.6.0_20).
	Type in expressions to have them evaluated.
	Type :help for more information.
	scala> def num_check(n: Int):Int = if ( (n % 3) == 0 || (n % 5) == 0 ) n else 0
	num_check: (n: Int)Int
	scala> def do_sum(x: Int):Int = if ( x == 3 ) 3 else num_check(x) + do_sum(x - 1)
	do_sum: (x: Int)Int
	scala> do_sum(10)
	res0: Int = 33
	scala> do_sum(100)
	res1: Int = 2418
	scala> do_sum(1000)
	res2: Int = 234168

view raw luhn.scala hosted with ❤ by GitHub

Wow, that went well and by the time I had googled to find the syntax for scala etc., clisp was downloaded and here goes https://gist.github.com/fc-unleashed/86ecd9aee76dcd8ec1decb3f15b84d6d