4 ms·

Show HN: Forsh – A Unix shell embedded in Forth

76 points by cowile2 9y ago

feelin_googley 9y ago
64-bit only?
- cowile2 9y ago
  A few of the words right now implicitly depend on machine word size to operate correctly. I could write versions that worked on 32-bit, but I don't have a 32-bit machine to test on.
spc476 9y ago
I did a Forth-like Unix shell in college (mid 90s) as a class project [1]. The differences I see from mine are: 1) I made Unix commands a first-class variable type. You could create a single Unix command and store it into a variable. You could also set up several commands as a pipe, and save that into a variable. 2) redirection and pipes are more Forth in style. Much like adding two values: 2 3 + To create a pipe, you create the two commands and then pipe them: cmd1 cmd2 | I'm looking over the code, and I don't think I finished redirection to tell the truth, but I can see it being easy to add it like: cmd1 "filename" | since variables are typed in my Forth-like language. It was a fun project to write (it even included history!) but as a practical shell? Not so much. The syntax left much to be desired for an interactive shell. [1] Unix systems programming. The class project was a Unix shell. I had, by that time, already written a Forth-like programming language on my own [2], which meant I could do the advanced shell (programmable) instead of the simple shell (command execution and redirection only). [2] I was seriously interested in Forth at the time.
- cowile2 9y ago
  Hello, everyone. I would have responded sooner but I spend most of my workday in a closed network for security reasons (defense contractor), and don't have much internet access over the course of the day. There is nothing stopping Forsh from being used that way. The convenience words from the README use a global variable to tell them where to build commands and overwrite the memory for every new command because the common case is that you as a user don't really care much about having arbitrary history (In any case, gforth already uses readline, so I get history for free). The words underneath all take that location as an argument on the stack. You could write some words that allocate space for each new command without changing the underlying libraries. The key to thinking about pipe words in Forsh is that they execute a given command and consume and/or leave a file pointer to a command's stdout on the stack. This is why there are multiple pipe words. They have different stack effects. `>|` (begin pipeline) only leaves a file pointer. `|` (continue pipeline) consumes and leaves a file pointer. `|>` (end pipeline) only consumes a file pointer. This allows the pipe words to interoperate with any file I/O words in gforth. If you want to "save a command to a variable", you just use a regular Forth word. [bracket] words make things work in compile mode. `: hack [c] echo [p] hack! $ ;` Executing hack will then build and execute the command. This also works with arbitrary pipeline fragments. I did my best with syntax, but existing shells have already aggressively minimized typing for short commands. The most I could do was have people type `l ` instead of `--` for long options and `s ` instead of `-` for short options. However, I find quoting much improved over existing shells. You specify the quote character when you type the command, so there is no escaping. You just pick a character that doesn't exist in the string. You are ok as long as your string does not included every printable ASCII character.
1024core 9y ago
Didn't the old Sun workstations boot into a Forth interpreter?
- spc476 9y ago
  Yes they did.
  - groovy2shoes 9y ago
    As did various offerings from Apple, IBM, and several others, once upon a time: https://en.wikipedia.org/wiki/Open_Firmware https://en.wikipedia.org/wiki/Open_Firmware
    - mhd 9y ago
      Ah, the joy of telling someone to hold down Command+Alt+O+F while booting just to eject their CD... (weirdly enough the most frequent Open Firmware use case on Macs)
- unixhero 9y ago
  Was / is Forth good and useful? Bonus; is it fun?
  - rijoja 9y ago
    It's fun to learn, and one of the first interpreted environments. What it enables is quick development on platforms with modest resources! Instead of compiling and executing you could develop quickly! Haven't used it for anything more than to do some examples in some tutorial. One thing that's nice about the language is that it's the simplest language you can implement on your own without going insane!
    - unixhero 9y ago
      Thanks for your reply!
    - deleted 9y ago
chubot 9y ago
Related :) Shell Has a Forth-like Quality http://www.oilshell.org/blog/2017/01/13.html http://www.oilshell.org/blog/2017/01/13.html https://news.ycombinator.com/item?id=13477842 https://news.ycombinator.com/item?id=13477842
deleted 9y ago
[deleted]

76 points by cowile2 9y ago

feelin_googley 9y ago

64-bit only?

cowile2 9y ago
A few of the words right now implicitly depend on machine word size to operate correctly. I could write versions that worked on 32-bit, but I don't have a 32-bit machine to test on.

spc476 9y ago

I did a Forth-like Unix shell in college (mid 90s) as a class project [1]. The differences I see from mine are: 1) I made Unix commands a first-class variable type. You could create a single Unix command and store it into a variable. You could also set up several commands as a pipe, and save that into a variable. 2) redirection and pipes are more Forth in style. Much like adding two values: 2 3 + To create a pipe, you create the two commands and then pipe them: cmd1 cmd2 | I'm looking over the code, and I don't think I finished redirection to tell the truth, but I can see it being easy to add it like: cmd1 "filename" | since variables are typed in my Forth-like language. It was a fun project to write (it even included history!) but as a practical shell? Not so much. The syntax left much to be desired for an interactive shell. [1] Unix systems programming. The class project was a Unix shell. I had, by that time, already written a Forth-like programming language on my own [2], which meant I could do the advanced shell (programmable) instead of the simple shell (command execution and redirection only). [2] I was seriously interested in Forth at the time.

cowile2 9y ago
Hello, everyone. I would have responded sooner but I spend most of my workday in a closed network for security reasons (defense contractor), and don't have much internet access over the course of the day. There is nothing stopping Forsh from being used that way. The convenience words from the README use a global variable to tell them where to build commands and overwrite the memory for every new command because the common case is that you as a user don't really care much about having arbitrary history (In any case, gforth already uses readline, so I get history for free). The words underneath all take that location as an argument on the stack. You could write some words that allocate space for each new command without changing the underlying libraries. The key to thinking about pipe words in Forsh is that they execute a given command and consume and/or leave a file pointer to a command's stdout on the stack. This is why there are multiple pipe words. They have different stack effects. `>|` (begin pipeline) only leaves a file pointer. `|` (continue pipeline) consumes and leaves a file pointer. `|>` (end pipeline) only consumes a file pointer. This allows the pipe words to interoperate with any file I/O words in gforth. If you want to "save a command to a variable", you just use a regular Forth word. [bracket] words make things work in compile mode. `: hack [c] echo [p] hack! $ ;` Executing hack will then build and execute the command. This also works with arbitrary pipeline fragments. I did my best with syntax, but existing shells have already aggressively minimized typing for short commands. The most I could do was have people type `l ` instead of `--` for long options and `s ` instead of `-` for short options. However, I find quoting much improved over existing shells. You specify the quote character when you type the command, so there is no escaping. You just pick a character that doesn't exist in the string. You are ok as long as your string does not included every printable ASCII character.

1024core 9y ago

Didn't the old Sun workstations boot into a Forth interpreter?

spc476 9y ago
Yes they did.
- groovy2shoes 9y ago
  As did various offerings from Apple, IBM, and several others, once upon a time: https://en.wikipedia.org/wiki/Open_Firmware https://en.wikipedia.org/wiki/Open_Firmware
  - mhd 9y ago
    Ah, the joy of telling someone to hold down Command+Alt+O+F while booting just to eject their CD... (weirdly enough the most frequent Open Firmware use case on Macs)
unixhero 9y ago
Was / is Forth good and useful? Bonus; is it fun?
- rijoja 9y ago
  It's fun to learn, and one of the first interpreted environments. What it enables is quick development on platforms with modest resources! Instead of compiling and executing you could develop quickly! Haven't used it for anything more than to do some examples in some tutorial. One thing that's nice about the language is that it's the simplest language you can implement on your own without going insane!
  - unixhero 9y ago
    Thanks for your reply!
  - deleted 9y ago

chubot 9y ago

Related :) Shell Has a Forth-like Quality http://www.oilshell.org/blog/2017/01/13.html http://www.oilshell.org/blog/2017/01/13.html https://news.ycombinator.com/item?id=13477842 https://news.ycombinator.com/item?id=13477842

deleted 9y ago

[deleted]