Re: [stack] initial stab at a wikipedia entry

--- In [email protected], John Nowak <john@...> wrote:
>
> 
> On Jan 2, 2009, at 9:50 AM, William Tanksley, Jr wrote:
> 
> > Not true -- a variable can be modeled (loosely) as an implicit
> > function of time. Forth provides local and global variables; locals
> > seem to make a language less concatenative, while globals don't hinder
> > it so much. (Naturally, globals have other problems.)
> 
> Global variables can be treated as functions that read/write some  
> state that gets passed through the program thanks to the monoidal  
> nature of things. Local variables cannot; their scopes are local and  
> hence you can't factor out code that references a local variable. The  
> only way of explaining locals is in terms of substitution.
> 
> I'm not sure if you think my explanation above rules out locals.

Well... In a Forth without local variables, you can easily "roll your
own" with globals A and B by putting code like this into a wrapper
secondary:-

A @ >R B @ >R

some work

R> B ! R> A !

A and B are globals that have been given a local scope. I don't known
if this would meet your criteria (and yes, I know why it's poor style
- this only goes to whether it can be done).