From: Kevin Bullock <kbullock@...>
Date: 2004-05-18T13:22:20+09:00
Subject: Re: Recursion depth

On May 14, 2004, at 4:44 PM, Ceri Storey wrote:

> On Sat, May 15, 2004 at 05:20:14AM +0900, Kevin Bullock wrote:
>> 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?
>
> In scheme, iteration is almost always defined as tail-recursion. Ergo,
> the interpreter / compiler must be able to transform tail-calls into a
> goto-like statement, so instead of pushing a new stack frame and then
> calling the function, the current stack frame is replaced with that of
> the called function.
>
> Sadly, ruby currently doesn't implement this, although I'd expect it'd
> be one of those features ear-marked for the RITE VM.
>
Thanks all. That's about what I expected. It seems as though optimizing 
tail recursion is something that Ruby ought to do, given that it draws 
so much other inspiration from functional languages.

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