Re: [stack] Advantages of cat, joy ..?

John Nowak wrote:
> William Tanksley wrote:
> > This is the big thing I don't
> > like about stack-copying behavior... Aside from the fact that
> > implementing it without an immutable stack is _hard_, it also assumes
> > the output for every operation is a single value at the top of the
> > stack.
> This may be a source of some confusion for us. If your programming  
> language is typed (or requires that all functions have inferable stack  
> effects), you don't need to use a stack in the implementation *at  
> all*. Accordingly, you certainly never need to copy it. There's no  
> efficiency penalty or implementation difficulty for something like the  
> banana combinator in this situation.

You're right in that I shouldn't have said "immutable stack". I don't
think that need be a source of confusion, because it's true that "stack
copying" behavior always introduces complexity, whether or not the
underlying implementation actually involves a stack. If your stack is
only a bookkeeping notion, then your bookkeeping is going to get a
little more complicated.

> I'm calling this current "concatenative FP" thing "Forthus". It has  
> the concatenative elements of Forth and the ideas of John Backus.  
> Back. Forth. Backus. Forthus. You get it.

I like it. I definitely look forward to reading more about it when it's
ready for that.

> - John

-Wm