Re: Back & Forth - Co-routines

On 23/03/2025 10:25 pm, Hans Bezemer wrote:

On 23-03-2025 04:03, dxf wrote:

On 23/03/2025 2:51 am, sjack wrote:

Ruvim <ruvim.pinka@gmail.com> wrote:
>

An artificial example:

>
While wondering down roads less taken, I took a path where
bacForth CUT: and -CUT were used in lieu of CATCH THROW .

>
Does anyone have a reference/details for this anywhere as I can't seem to
find anything?
>
A possibly useful hit but the doc is locked away:
>
https://doi.org/10.1145/165628.165637

 
Found it! Try this one: https://www.complang.tuwien.ac.at/anton/euroforth/ef96/gassanenko96b.txt
 
But I'm gonna spoil it for you: BacForth has an extra "L" stack. CUT: and -CUT use it. You might wanna use this one if you REALLY want it: https://sourceforge.net/p/forth-4th/code/HEAD/tree/trunk/4th.src/lib/stack.4th
 
It's code for a light weight stack. BTW, TRACKING is missing as well. It might have to do with this one? https://sourceforge.net/p/forth-4th/code/HEAD/tree/trunk/4th.src/lib/backtrak.4th
 
: CUT:      \ mark the beginning of the fragment to cut
    R>  RP@ >L                   \ copy r-stack top addr. to L-stack
        BACK LDROP TRACKING      \ delete this mark when backtracking
    >R ;
: -CUT  R> L> RP! >R ;  \ delete return points upto the marked addr.
: -NOCUT    \ remove the mark, but not the return points
    R>
      L> RP@ - >R                \ keep the mark as a relative address
      BACK R> RP@ + >L  TRACKING \ restore it when backtracking
    >R ;

Thank you (and sjack) for chasing down this one.  More detail appears to be
available in the SP-Forth sources directory:  \devel\~profit\lib\bac4th.f

A CP1251 to Unicode converter is here:
https://convertcyrillic.com/#/convert