Is Forth really homoiconic? I’m asking as a recent fan of Forth. I would’ve thought to describe it as having strong, interactive metaprogramming but not necessarily homoiconic. Unless ‘code = data, data = code’ because they’re all bytes… haha.
Postscript would count as homoiconic, I’d think. Though I haven’t actually seen programs that so this.
I think Forth counts, in a "Turing-complete" sense of homoiconicity. A Forth program in a classic indirect threaded system can self-modify, reach in and change core interpreter words during execution. But it isn't obeying any formal soundness principle, since it's just a thin layer over the machine.
Compiled Forths might opt to wall off some of those options behind the compiler interface, in effect making the language slightly less far-reaching.
I could see that. Which I guess would put assembly into the homoiconic bucket. I think it fits the concept but sure isn’t the same as what people think of with Lisp, etc… lol.
Had this discussion on Discord as well. Like most things Forth it depends how you use it. If we consider the classic indirect threaded systems, then every field in a definition is an address called an execution token (XT). In most systems you can convert an XT back into a text label. This allows pretty simple de-compiling for example.
It is trivial to collect those Xts as data and execute them later.
CREATE XT-LIST ] THESE WORDS COULD BE FORTH CODE [
XT-LIST now contains six XTs. They can now be read one XT at a time and executed.
So if one accepts that those XTs are data, BUT they are also code since they can be "executed" by the Forth VM then I think we can say Forth is homoiconic.
However if that doesn't suffice it is perfectly legal to pass text strings to EVALUATE.
: TEST S" THESE WORDS COULD BE FORTH CODE" EVALUATE ;
Aha, that’s pretty awesome. I’m familiar with XT’s but hadn’t thought of using them that way. And didn’t know that you can convert back to text.
I’m going to have to do more Forth. And I have a sudden urge to go write some silly self-modifying assembly, if current processors even allow that anymore.
Postscript would count as homoiconic, I’d think. Though I haven’t actually seen programs that so this.