Re: [stack] disallowing recursive definitions

John Cowan <[email protected]> wrote:
> William Tanksley, Jr scripsit:
>  > Now, interestingly, a concatenative tail-call cannot do this. Does
>  > this imply some superiority for concatenative optimizers? :-)

I'll reply to both of your messages in one.

>  No.  All you do is do an arbitrary stack shuffle before the tail call.

Then the analysis difficulty (if there is any) is obviously in the
shuffle, not in the tail-call. The analytical problem with an
applicative tail-call is that the 'shuffle' happens at the same time
as the call.

> With a concatenative tail-call you're passing the stack as an
> argument. In other words, you pass the entire state of the program!

Yes, this is how concatenative languages are modeled. That's how
*every* step in their execution is modeled, not just tail-calls or
calls. If this were a problem, concatenative languages would be
universally problematic, not merely problematic in the presence of
tail-calls.

>  John Cowan        http://www.ccil.org/~cowan          [email protected]

-Wm