From: Kevin Bullock <kbullock@...>
Date: 2004-05-15T05:20:14+09:00
Subject: Recursion depth

Take the following two recursive implementations of Euclid's algorithm, 
the first in Guile, the second in Ruby:

(define (euclid m n)
	(if (= n 0)
		m
		(euclid n (remainder m n))))

def euclid(m, n)
     if n == 0 then m
     else euclid(n, m % n)
     end
end

The results of running each function (which are both the same) are as 
follows:

guile> (euclid (random (expt 10 1000)) (random (expt 10 1000)))

irb(main):001:0> euclid(rand(10**1000),rand(10**1000))
SystemStackError: stack level too deep

Why is it that guile can handle such recursion but Ruby can't? Is it 
that guile is implemented with iterative recursion in mind, and so 
optimizes for it better?

Pacem in terris / Mir / Shanti / Salaam / Heiwa
Kevin R. Bullock