Re: QUIT and ABORT

On 19/05/2025 8:52 pm, Ruvim wrote:

On 2025-05-18 18:27, dxf wrote:

On 18/05/2025 6:16 pm, Ruvim wrote:

...
Note that in `error` you don't transfer control to `(abort)` only in the case of `-56`.

>
I transfer control to (abort) except in the case of -56 where it passes to (quit).

 
Hence, `-56` is a special case in your implementation.

No more special than what ANS did for -1 and -2 .

Another question is how are `evaluate` and `included` implemented?
>
I assume they use `catch`.

>
INCLUDE uses CATCH , EVALUATE does not.

 
If any of the following tests fail, then `evaluate` (or `throw`) is not compliant:
 
  t{ 9 s" 1 throw" ' evaluate catch nip nip -> 9 1 }t
  t{ char | parse s" 1 throw" ' evaluate catch nip nip| evaluate -> 1 }t
 
or
 
  9 s" 1 throw" ' evaluate catch nip nip swap . .
  char | parse 9 s" 1 throw" ' evaluate catch nip nip| evaluate swap . .
  \ both lines shall print "9 1" in a standard Forth system.

Yes, my EVALUATE has limitations.

Then your Forth system probably shows the following behavior in its terminal:
>
   999 -56 throw
      ok  999 <
>
   s" 999 -56 throw" evaluate
      ok
>
Of course, the first case shows a non-standard behavior.

>
The first case is correct behaviour for a system that implements a catchable QUIT.

 
Yes, it can be correct in the sense that it is in accordance with your system documentation. But it is not in accordance with the ANS Forth standard (as well as Forth-2012).

Table 9.2 expressly allows systems to implement a catchable QUIT.
 

You interpret the reservation of `-56` for `quit` as a provision to make `quit` catchable.

Correct.  I'm grateful for serious opponents as they do my homework for me.
If I had any concerns about a catchable QUIT beforehand, your posts have
resolved them.  I've seen no convincing rationale that QUIT should not have
the same entitlement as ABORT and ABORT" .

But catchable `quit` is not ANS Forth compliant. And your deviation in the behavior of `throw` is also not ANS compliant.

That would be your interpretation.  You can resolve it for future standards
by putting it to the committee.