29 Feb
2000
29 Feb
'00
1:41 p.m.
This is almost 20 year old memory cells trying to
activate here, but I
thought Forth was generally implemented by "compilation" into a non-standard
pCode which was then run interpretively by a stack oriented run time engine.
That's one way of doing it, but the most traditional (and still most
popular, at least from what I see) way of doing it is to compile
straight to threaded machine code.
Note that even though threaded code is usually most commonly associated
with Forth and other "non-traditional" languages, the technique
is applicable to old-line languages as well. For example, Fortran IV
compilers on the PDP-11 could optionally compile to threaded machine code,
usually producing smaller object code as a result.
Thus, I would have said it was a stack oriented
language. But I guess it
depends on if you're looking at the language itself or how it is normally
executed?
To me, at least, threaded means "you call a subroutine for everything".
For instance, if you want to add two numbers, you push them onto a
(or the) stack and call the add routine. It's the extreme opositte
of "inline" code, to the point where you can think that you're working
on a "virtual" machine that doesn't have the limitations of your
"real" machine (probably why you've confused Forth with p-Code type
intermediate representations - after all, conceptually they aren't that
different!)
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
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