Re: FP number syntax

On 1/01/2025 8:51 am, Anton Ertl wrote:

Paul Rubin <no.email@nospam.invalid> writes:

anton@mips.complang.tuwien.ac.at (Anton Ertl) writes:

<https://forth-standard.org/standard/double#subsection.8.3.1>

>
Aha, thanks.  Similarly 8.3.2 for DPANS94.  Oddly, in gforth, "123.45"
pushes 12345 0.  I can understand "123." is a number (123) followed by a
decimal point, but I'd expect the 45 to either be invalid or another
number, giving 123 0 45.

 
Traditionally, Forth has used the syntax 123.45 for fixed-point
numbers.  You get the same number on the stack as with the standard
"12345.", and in addition, the (user) variable DPL is set to indicate
the position of the decimal point.  I have no idea how this crude way
was used in practice, but in any case, Gforth implements this feature.

It's possible this came from Kitt Peak Forth (on which Forth-77 was based)
and picked up by Fig-forth.  'Starting Forth' (Forth Inc) supported
'embedded punctuation' - a range of characters including / # etc to simulate
various formatting e.g. time and date.

 
The Forth-94 standardizers were apparently less convinced, so they
standardized neither numbers with an embedded decimal point, nor DPL.

To support DPL I have >NUMBER increment it for every digit successfully
converted.  While most systems today have DPL (?) usage is probably too
diverse to standardize.