Standard compliance for systems (was: single-xt approach in the standard)

On 2024-09-23 09:28, dxf wrote:

On 23/09/2024 2:57 am, Ruvim wrote:

...

NB: Keeping floating-point numbers on the data stack does not make a Forth system non-standard, but it merely adds an environmental restriction to this system, see the section "12.4.1.4 Environmental restrictions" in Forth-2012.

 I hadn't seen that.  Forth-94 stated floating-point stack was "the default".
If the only change is that the latter is clarified, then no harm done.
Implementing separate stack on an 8-bit cpu would be expensive and a
performance killer. 

As to being "far simpler" to program, similar appeals
are made in respect of locals.
I make it a point to program as if I had a
unified stack just to see if the claim is true.

A real problem was to create programs that work with floating point numbers and would work correctly both on a unified fp stack and on a separate fp stack.
See the section "C.7.2 Separate Floating-point Stack is now Standard" in Forth-2012 <https://forth-standard.org/standard/diff#subsection.C.7.2>

 

2) Quote-delimited character interpretation ('A') makes programs simpler, this seems obvious.

 Only thing obvious is it's an import from other languages and redundant.
Forth Inc stated they didn't agree with it but eventually provided it.
 

Using `'x'` is simpler and shorter than `[char] x` or `char x` depending on the context.
And even if you redefine `[char]` to provide the expected interpretation semantics, like:
   : [char] state @ if postpone [char] else char then ; immediate
`[char] x` is still longer than `'x'` and provides no additional benefit to programs.

3) Two buffers for interpretive `s"` makes debugging simpler, because you can test words like `rename-file` interactively, see "A.17.3.4 Other transient regions" in Forth-2012.

 I have  >PAD ( adr u -- adr2 u )  for that.  Uses existing resources and is
more flexible.
 

The phrase:
   s" foo" s" bar" rename-file .
is simpler than:
   s" foo" >pad s" bar" rename-file .
What advantages does the latter provide to users over the former?
If a Forth system is so limited in memory that it cannot provide two buffers for `s"`, it *might* provide only one buffer and declare the corresponding environmental restriction according to the sections:
- 5.1.1 System compliance
| An otherwise Standard System (Subset) that fails to comply
| with one or more of the minimum values or ranges specified
| in "3 Usage requirements" and its sub-sections has
| environmental restrictions.
- 5.1.2 System labeling
| The phrase "with Environmental Restrictions" shall be
| appended to the label of a Standard System (Subset) that
| has environmental restrictions.
- 11.3 Additional usage requirements, 11.3.4 Other transient regions
| The system provides transient buffers for `S"` and `S\"`
| regions strings. These buffers shall be no less than 80
| characters in length, and there shall be at least two buffers.
--
Ruvim