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It may look more high-level than something like C, but it is actually no more high level than a macro assembler with registers eliminated. As there's no syntax tree, essentially every word that is parsed from the input stream is replaced with a subroutine call. So the resulting FORTH code is nothing but a series of subroutine calls.

In my experience quite often writing in assembler is easier than FORTH unless you have a strategy and self discipline, which when acquired makes one a whole lot more productive than using assembler, and arguably more so than a high level language. There're no pointer arithmetics, no rudimentary type checking, not even an array type (you have cells and addresses). There is nothing that throws an error except things like stack over/under-flow checks, and if you are lucky your code will crash. If not debugging can be tricky. Stack imbalances won't be reported/checked for you, there is no bounds checking for anything (not even structs). But there are conventions/strategies to prevent these kinds of bugs from happening that one needs to either discover for themselves, or find out in books (the book Thinking Forth helps, but is not enough I would say).

Working with the stack can be more difficult than with registers, although the latter can be easily simulated with variables, which is often frowned upon. But words like CREATE ... DOES> enables meta-programming that helps with generating code with code, and makes it quite powerful, but can make your code complicated to reason about (see the concepts of compilation vs. execution vs. interpretation semantics described in ANS Forth).

In the end the appeal of FORTH for me is in its "simplicity" (but nowhere any ease of use as it requires mastery of laying out code in memory as you would do in an assembler without any help from the language itself), its overall philosophy (see Chuck Moore's A Problem Oriented Language) on focusing on the nature of the problem rather than thinking in terms of the tools/language given to you (build a "language" for the problem), and providing solutions with as minimal "cruft" as possible.

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cess11 4 days ago | parent | next [-]

Factor addresses some of these concerns and instead of giving you a bare metal REPL you get a Smalltalk-like image: https://factorcode.org/

It's rather neat.

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chipwits 3 days ago | parent [-]

I was just looking at Factor yesterday. I find it cool that it was originally created as a scripting language for a game engine.

	▲	cess11 3 days ago \| parent [-]
		It's great fun. The environment is pretty mature by now and for being a niche language there's lots of public code to study. I'm not sure but I think John Benediktsson is still the maintainer, and at least a few years ago he was active in their Discord server. His blog is a very good resource. Some people are doing AoC:s in Factor, also worth a look. https://re.factorcode.org/ https://github.com/gifti258/aoc-factor

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sph 4 days ago | parent | prev | next [-]

> Working with the stack can be more difficult than with registers, although the latter can be easily simulated with variables, which is often frowned upon

Yet every time I hear experienced Forth developers recommending to use more variables, and that newbies tend to eschew them, making the code much harder to read and understand than it is necessary.

You become a true Forth programmer once you go past the code golf and stack juggle phase.

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drivers99 4 days ago | parent | prev [-]

Anything that you say is missing can be added. I'm no expert but when I had some confusion about the stack I would create a word that did something in a balanced way, test it quickly, and use that word instead to build on. Forth makes it easy to climb the levels abstraction quickly.

The method that it uses to interpret/compile a word varies by implementation. Subroutine call is just one of them.

	▲	selvor 4 days ago \| parent [-]
		> Anything that you say is missing can be added. For sure, it can be extended indefinitely. It's good that you made that clear. You can add a C compiler if you like (see Dusk OS) even, or a generic BNF parser generator (see Bradford Rodriguez) into "the language". Anything that you devise for code correctness, and static analysis can be added. My points about the lack of these language features were towards the previous comment about FORTH looking "more high-level than C". These are definitely major shortcoming for an inexperienced programmer to be able to do anything reasonably complex in FORTH (similar to using assembly). > ... I would create a word that did something in a balanced way, test it quickly, and use that word instead to build on. Forth makes it easy to climb the levels abstraction quickly. I would say any programming language with functions provide the same ease by that definition. That is, in each you can write a set of functions, than use them to compose higher level functions ad infinitum until you create a DSL as essentially a collection of functions for your problem space. Although doing so in C-like languages syntactically it may look more like Lisp than FORTH. In FORTH it looks more concise, and reads left-to-right thanks to it being accidentally a "concatenative language" with point-free notation and combinatory calculus roots. A great example of this being formalized is Joy by Manfred von Thun. So I think what makes FORTH unique is more of the philosophy around it (again, see POL book by Chuck), which is a kind of zealous struggle for simplicity, but not easy, and keeping the problem in focus and not ignoring what's inside the boxes you build upon. You could say it's a panacea for yak-shaving if done right. Concrete examples for what FORTH does away in its search for simplicity and avoidance of yak-shaving, here are a few: - no in-fix notation or ASTs: computers understand post/reverse-Polish by default by virtue of them being a stack(/register) machine, the programmer can do this work without major difficulty, - no filesystem: blocks and table of block indices are enough most of the time, - no floating point: fixed point is good enough for most problems, - no classes, arrays, structs: you can build your own constructs suited for your problem as they are needed, there is no one size fits all solution, Etc. The list goes on. Some of these are added into the so-called standards, but some argue trying to standardize FORTH defeats itself. > The method that it uses to interpret/compile a word varies by implementation. Subroutine call is just one of them. I used a vague terminology there, and should have clarified by saying "regardless of the threading model". What I meant was that effectively the FORTH source compilation is a one step pass that converts string tokens into series of "subroutine" (conceptually) calls that map 1:1 with the source code (homoiconicity); direct/indirected threaded, token threaded, or subroutine threaded all effectively is laying out/interpreting a series of subroutine calls, including those in FORTH CPUs like Harris RTX or GA144.