34
bjForth v0.0.3 is out!
(github.com)
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
this post was submitted on 29 Dec 2024
34 points (94.7% liked)
Programming
17701 readers
224 users here now
Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!
Cross posting is strongly encouraged in the instance. If you feel your post or another person's post makes sense in another community cross post into it.
Hope you enjoy the instance!
Rules
Rules
- Follow the programming.dev instance rules
- Keep content related to programming in some way
- If you're posting long videos try to add in some form of tldr for those who don't want to watch videos
Wormhole
Follow the wormhole through a path of communities !webdev@programming.dev
founded 2 years ago
MODERATORS
Not knowing forth, why would you ever want this language?
Besides the fun of stretching your mental muscles to think in a different paradigm, Forth is usually used in the embedded devices domain (like that of the earlier Mars rover I forgot the name of).
This project for me is mostly for the excitement and joy I get out of implementing a Forth (which is usually done in Assembler and C) on the JVM. While I managed to keep the semantics the same the underlying machinery is vastly different from, say, GForth. I find this quite a pleasing exercise.
Last but not least, if you like concatenative but were unable to practice fun on the JVM, bjForth may be what you're looking for.
Hope this answers your question.
It looks to me to be the same paradigm as pure functional languages, is this false? The only difference to lisp seems syntactic.
Forth is stackier.
Yeah that's what I meant with syntactically. You could act as if in Lisp arguments to functions are pushing on the stack, and functions are removing them and pushing the result back.
In Forth, though, the number of results pushed to the stack after an execution of a word could be a function of the input rather than a single value or even a fixed number of values.
Likewise, the number of arguments that a word pops from the stack could be a function of a value pushed earlier to the stack.
That's what macros are and let you do in Lisp
Perhaps you could explain exactly what you mean?
If you don't know Lisp, it'd probably take too long for me explain (i.e. I don't want to). Basically, macros let you rewrite your code arbitrarily, which would have the same effect as arbitrarily modifying the stack.
You are making the extremely incorrect presumption that I am unfamiliar with Lisp and how macros work. What is unclear to me is how you specifically think that arbitrarily rewriting code at macro expansion time is exactly equivalent to arbitrarily manipulating the stack at runtime.
No. Roughly speaking, functional languages implicitly manage the stack for you, whereas Forth requires you to manage it explicitly.
Not really I'm afraid. Effects can be anywhere and they are not wrapped at all.
In technical terms it's stack-oriented meaning the only way for functions (called "words") to interact with each other is via a parameter stack.
Here's an example:
TIMES-10is a word which pops one parameter from stack and pushes the result of its calculation onto stack. The( x -- y)is a comment which conventionally documents the "stack effect" of the word.Now when you type
12and press RETURN, the integer 12 is pushed onto stack. ThenTIMES-10is called which in turn pushes10onto stack and invokes*which pops two values from stack and multiplies them and pushes the result onto stack.That's why when type
.Sto see the contents of the stack, you get120in response.Another example is
This simple example demonstrates the reverse Polish notation (RPN) Forth uses. The arithmetic expression is equal to
5 * (20 - 10)the result of which is pushed onto stack.PS: One of the strengths of Forth is the ability to build a vocabulary (of words) around a particular problem in bottom-to-top fashion, much like Lisp. PPS: If you're ever interested to learn Forth, Starting Forth is a fantastic resource.
Forth is fairly different AFAIK. If you want a "Forth style" language for general purpose, with more "batteries included", try Factor! It's a really nice language.