I have made a living with Forth since 1981. I have written very few new Forth kernels, but have ported them to many CPU architectures. Forth is no longer fashionable, but it works.
Writing a new Forth may be an interesting project, but you will not write a good one until you have a few applications under your belt. Forth is a very subtle language. The internet is full of abandoned Forth kernel projects. Many of these may well have succeeded if they had a purpose that was not yet satisfied.
It is perfectly possible to write large applications in Forth. One of our clients has an application of 1.4 million lines of Forth source code. It is hosted on VFX Forth, which compiles Forth to native code. The VFX version runs at least ten times faster than the previous threaded code version, built on MPE's ProForth compiler.
The guy who invented NodeJS (a "fashionable" giant hack) got up and said he regretted it and now uses Go. Did that stop anyone from running up the tech debt with NodeJS? After all, "everyone is doing it!" So easy to start banging out JavaScript...
At the other extreme you have Swift which is not Good (as opposed to no good) until V5 which is now obsoleted by V6. Do we all know how screwed Apple is when it comes to LLM training coverage of Swift 5 or 6? Short of their own codebase (and even then), where are they going to get enough training data to help all the Vibe Coders and novices? Could take years to resolve this.
Weird future, eh? So FORTH may not be "fashionable" but it is hella fun and very good in a number of dimensions. With the right LLM interfaces (which love large libraries of concise word-like primitives), world domination is assured.
I'm really curious, how many people collaborate on that 1.4MLOC application? I'd think you might end up with "too many cooks in the kitchen" sort of problems because of how much power the language gives everybody.
It's a sort of silly trivial example... but I've watched multiple python codebases slowly become unmaintainable because Python has no way to enforce what can be called or overridden by instances or subclasses, and the org grew beyond its ability to enforce discipline about it in code review.
I feel like Forth would offer orders of magnitude more "temptations" for somebody who just needs to get something done, but I've never seen it done at scale.
Over the last twenty years or so, I have written serious Forth code generators for six CPU architectures. There's only one code generation algorithm that's not regularly present in most Pasgol family compilers. The results are the VFX Forth systems at http://www.mpeforth.com.
Writing a new Forth may be an interesting project, but you will not write a good one until you have a few applications under your belt. Forth is a very subtle language. The internet is full of abandoned Forth kernel projects. Many of these may well have succeeded if they had a purpose that was not yet satisfied.
It is perfectly possible to write large applications in Forth. One of our clients has an application of 1.4 million lines of Forth source code. It is hosted on VFX Forth, which compiles Forth to native code. The VFX version runs at least ten times faster than the previous threaded code version, built on MPE's ProForth compiler.