I wonder why not reimplement coreutils as library functions, to be used within an ad-hoc REPL. It would be much more flexible and extensible.
AFAIK, originally the reason why they were made as programs was that the available programming languages were too cumbersome for such use. Now we have plenty of experience making lightweight scripting languages that are pleasant to use in a live environment (vs premade script), so why give up the flexibility of ad-hoc scripting?
The problem is POSIX. It says operating systems must have mv, cp and all that stuff. This is the reason why people say Linux is not an operating system.
> I wonder why not reimplement coreutils as library functions, to be used within an ad-hoc REPL.
Funny you mention that. I've been working privately on such a "systems programming REPL" in my free time. Basically a freestanding Lisp with pointers and built-in Linux system calls. It's been a huge challenge trying to bootstrap and get the garbage collector working without any libc support, still haven't cracked it.
Languages like Python and Ruby already have system call capabilities. You can literally do anything with those calls. So this already exists in some form, albeit not in the extreme form I envisioned.
Are you building something similar to babashka? Would you be able to figure out what they did with babashka to figure out what you've been unable to do, or are you challenging yourself?