Where Forth really shines is bootstrapping something really novel.
Take an entirely new CPU. A reasonable Forth kernel can be written in as little as 1k assembly code, obviously dependent on said CPU instruction forms and sizes.
Once that is done and one has working serial comms, upload a dictionary at it and get a full featured environment quickly.
Then, write system dependent words in assembly to complete the basic picture and get stuff done.
I have seen skilled Forth users do this kind of thing in a day.
Yeah, FORTH is really good at this. You can start exercising stuff at the hardware level in just a few hours. It's fantastic for system bring-up, and I've used it several times for this.
FORTH is terrible at scaling to large systems, though. It's also terrible at hard real-time tasks (like games) or anything requiring much in the way of data structures (FORTH's memory management is about as primitive as you can get).
I am not sure in which universe games can be described as hard real-time tasks but it's surely not the one we live in. Either way, it's laughable to say that Forth is terrible at hard real-time (see NASA link below).
The rest of your arguments are also similarly terrible which makes me question your familiarity with Forth.
The telescope application was not very demanding real-time. It basically did slewing control, and you have sufficient overhead to do that in BASIC; milliseconds don't matter very much. Telescopes are a classic example of FORTH's success; the problem comes when you try to extrapolate from that into other problem areas.
The attempts I've seen to make FORTH work in a real-time game have all ended in failure. There are technical reasons for this (high cost of inner interpreter overhead, lack of dynamic memory allocation, program structure that makes it difficult to work in large teams) as well as social ones (mostly lack of objective evaluation of quality, and other immature engineering practices).
Dynamic memory allocation seems like something you'd generally want to avoid in real-time programs and games. Slab allocation is often used (I think that's the right term, allocate a large chunk of memory at startup, bump a pointer to allocate, reset the pointer to free all memory at once), and that's simple to implement in Forth.
If inner interpreter overhead is an issue, there are well known solutions to that as well. Subroutine threading removes the inner interpreter entirely, and makes it simple to implement inlining in the compiler, and then there's always the inline assembly approach.
I'm using Forth for real-time data collection, and have been very pleased with it's speed. I'm able to reliably and consistently grab sensor readings over a 500 uS period with an average jitter below 1.2 uS on a Cortex M4. Yet I still get the flexibility of a dynamic language. It's a nice environment after the addition of some routines (coded in C) for dynamically allocated arrays with better safety mechanisms. In my case I'm not responding to various user inputs, etc, but the cost of the inner interpreter appears to be on par with - or better than - various bytecode interpreted languages.
”There are technical reasons for this (high cost of inner interpreter overhead, lack of dynamic memory allocation, program structure that makes it difficult to work in large teams)”
I think none of those have much to do with real time, per se.
Inner interpreter overhead may affect performance, but a real time game need not perform well.
Lack of dynamic memory allocation can’t be an issue, as one can always implement it in Forth.
I don’t contest that difficulty to work in large teams is an issue with Forth, but that doesn’t affect ability to write real-time games; it affects ability to write large/complex games.
Forth was used for a few commercial games in the 80's(e.g. Starflight), but game programming tends towards getting knee-deep in a statically allocated global state with a large, bespoken update procedure, both of which run contrary to Moore's preferred style of Forth(small word sizes, most things on the stack). So relative to macroassembers, the obvious competitor, most of the potential in Forth can't be usefully realized without reframing it as a metaprogramming tool that emits an assembler binary(In which case - you are going for high level abstraction. There are languages that give you lots of those without effort on your part.)
Forth does excel at low memory usage, but the gains are only realized when you don't have a static allocation driving things. Game scenes and most real-time code are statically allocated because statics will allow you to "deliver on what you promise" - if memory is maxed out, the system still hits its deadlines.
I guess what you are saying is that while forth is capable, it doesn't really give you anything over using assembler for low-level programming. And if you want high-level abstraction, you can always use C anyway.
I had to lookup "opinionated" to make sure I understand this statement correctly...
Forth is on the contrary very opinionated. When you want to implement something in Forth, you have to take into account it's very limited ability to support complexity. Which forces you to think about the problem until you can code a simple enough solution for Forth.
It's a severe limitation, but it's one of the rare cases where a limitation is actually a feature. Forth forces its opinion about simplicity on you and that's a good thing in my opinion, because people tend to underestimate the exponential nature of complexity growth: adding a parameter to a procedure at least doubles the amount of unit tests you have to perform on it; add three parameters and that's a 8x the tests.
But it also makes Forth far less fit for task where handling nightmarish complexities is the main topic. If you can't cut the Gordian knot, you lose.
In the sense that there are no types (or only one, depending on how you look at it), that its inventor eschews standardization, that there are literally no keywords and that the basic premise of the language is that it, the interpreter, the application and the compiler are the same thing, it's not at all opinionated.
You make an interesting point, but what you describe is about the only sense in which I'd respect calling Forth opinionated. In every other sense, walking into a new Forth application is potentially like walking into a new language.
As a good example of how unopinionated it is, here are the jonesforth implementations of the IF and THEN words:
: IF IMMEDIATE ' 0BRANCH , HERE @ 0 , ;
: THEN IMMEDIATE DUP HERE @ SWAP - SWAP ! ;
Don't need those words? Don't implement them and make your own branching abstraction. Feel like you spend too much time juggling the stack? Implement named parameters and local variables. Need records or structs? Do it. Need an object system? Go for it.
> walking into a new Forth application is potentially like walking into a new language
This is how walking into an application in any language (but yes especially Forth and Lisp(s)) is supposed to be but most are doing it wrong by repeating a lot of boilerplate.
If you have a boilerplate in your Forth, you are doing it wrong, it seems.
> Forth is not the language. Forth the language captures nothing, it's a moving target. Chuck Moore constantly tweaks the language and largely dismisses the ANS standard as rooted in the past and bloated. Forth is the approach to engineering aiming to produce as small, simple and optimal system as possible, by shaving off as many requirements of every imaginable kind as you can.
> That's why its metaprogramming is so amazingly compact. It's similar to Lisp's metaprogramming in much the same way bacterial genetic code is similar to that of humans – both reproduce. Humans also do many other things that bacteria can't (…No compatibility. No files. No operating system). And have a ton of useless junk in their DNA, their bodies and their habitat.
> Bacteria have no junk in their DNA. Junk slows down the copying of the DNA which creates a reproduction bottleneck so junk mutations can't compete. If it can be eliminated, it should. Bacteria are small, simple, optimal systems, with as many requirements shaved off as possible.
VLSI design is pretty complex, yet Chuck Moore figured it out in mere 500 lines of Forth and successfully manufactured chips designed with his own tools: https://colorforth.github.io/vlsi.html
> But it also makes Forth far less fit for task where handling nightmarish complexities is the main topic. If you can't cut the Gordian knot, you lose.
Maybe in a monolithic program. But I could see successfully tackling some very complex problems with a swarm of Forth programs that are individually very clean and simple.
That sort of approach is presumably one of the basic ideas behind Green Arrays.
Embedded image USEMAPs make me feel old. I remember when you couldn't even reliably support them in all web browsers. For each clickable image map you also needed a GET/POST form 'CGI' program that was passed only relative image coordinates of the click and had to decode it server side.
I remember that 199X trend, where you would re-create an FBI warning: orange tape, gif of a spinning warning light, etc. Expect this to be the same era joke.
I tend to love the website aesthetics. It has some quirks but hierarchical presentation of information is hard to beat. The guy's writing style is amusing as well. Thumbs up for the great find.
