Re: [stack] S-K Construction of Dip?

On 19/4/07 12:40 AM, "William Tanksley, Jr" <[email protected]> wrote:
> 
> Manfred Von Thun <[email protected] <mailto:m.vonthun%40latrobe.edu.au>
> > wrote:
> 
>> > "William Tanksley, Jr" <[email protected]
>> <mailto:wtanksleyjr%40gmail.com> > wrote:
>>> > > Again, I was talking about Joy. Joy is not flat; it doesn't depend on
>>> > > your perspective. L _is_ flat; again, it doesn't depend on your
>>> > > perspective.
> 
>> > See your own comment above. You agree that L is concatenative (and flat),
>> > and that Joy is concatenative (but not flat). I thought it was clear that
>> > they accept the same programs ­ more or less, perhaps. If so, then
>> > flatness is in the eye of the beholder.
> 
> But they do not accept the same programs. L accepts many more programs
> than Joy does. L may even be more expressive than Joy (although I
> haven't examined it to see whether it actually is).
> 
You are exactly right about L++ (in the terminology of my original post),
but not about L.
Reminder: L and L++ both use a stack of foyers, but they differ in whether
they allow
unmatched ³[³ before ³.² In a nutshell, again for both L and L++ :

³[³ starts a new foyer,
³]² appends the current foyer as a list to the previous foyer, and
³.² executes the current foyer on the foyer below.
> 
But there is a difference:

L does not allow the sequence ³[³ ... ³.² because of unmatched brackets.
L++ does allow this sequence, and as you rightly observe, it resembles Forth
immediates.

I still maintain that L = Joy, and agree that L++ is a superset. But I am
not at all sure
whether the extras that L++ can do cannot also be achieved (in a different
way) by
using existing list- (and hence program-) manipulators. I just don¹t know.

I meant this posting to be more detailed, sorry Billy. But I got sidetracked
by downloading
the Factor tarfile and inspecting quite a lot of the files. A most
impressive piece of work,
congratulations to the author(s).

  - Manfred



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