Wow they actually did it! Congratulations and welcome to the age of second-gen systems languages!
Seems one of the main reasons is to use Rust’s thread safety to enable “concurrent mode”. Anyone with the knowledge able to explain what advantages that would yield for an end fish user?
One big, long-standing issue is that fish can’t run builtins, blocks or functions in the background or at the same time.
That means a pipeline like
seq 1 5 | while read -l line echo line; sleep 0.1; end | while read -l line echo line; sleep 0.1 endwill have to wait for the first while loop to complete, which takes 0.5s, and then run the second.
So it takes 0.5s until you get the first output and a full second until you get all of it.
Making this concurrent means you get the first line immediately and all of it in 0.5s.
While this is an egregious example, it makes all
builtin | builtinpipelines slower.Other shells solve this via subshells - they fork off a process for the middle part of the pipeline at least. That has some downsides in that it’s annoyingly leaky - you can’t set variables or create a background job in those sections and then wait for them outside, because it’s a new process and so the outer shell never sees them.
Here’s one issue they hope to solve with this rewrite: https://github.com/fish-shell/fish-shell/issues/238
End user shouldn’t care what PL the software is written in. Their advantages and disadvantages are meaningful for developers only.
Except they affect the end result.
While I agree, most people shouldn’t have to be concerned with it, you can’t deny the resource impacts of various languages, libraries and frameworks, like compare the memory usage of Discord or Teams with those of FOSS chat applications, and you’ll notice those two consistently eating much more memory. You can also compare compute speeds of a higher level language like Python vs lower level languages like Rust and you’ll find that Rust is quite a bit faster (though generally takes more dev time). So yes, users shouldn’t have to be concerned with involved languages, but if you’re running something on a low-resource device, such as a Raspberry Pi, those little details can make all the difference.
@Chewy7324 seems like it would be easier to have programmers port it than fish
These rewrites in rust are merely just training exercises for those doing it. It wasn’t needed and in most cases isnt used.
Large parts of the rewrite came from contributors who had never worked on fish before.
That’s pretty useful alone.
And there’s this:
Thread Safety
Allowing background functions and concurrent functions has been a goal for many years. I have been nursing a long-lived branch which allows full threaded execution. But though the changes are small, I have been reluctant to propose them, because they will make reasoning about the shell internals too complex: it is difficult in C++ to check and enforce what crosses thread boundaries.
This is Rust’s bread and butter: we will encode thread requirements into our types, making it explicit and compiler-checked, via Send and Sync. Rust will allow turning on concurrent mode in a safe way, with a manageable increase in complexity, finally enabling this feature.
They did it “for the vibes”
Vibes are just as important to free/open source software as proprietary software and although there were solid technical reasons for the port, the PR outcomes are added benefits.
Angry downvotes because people don’t like to hear that a meme language is a meme language.
Probably not “angry” downvotes. OP provided a link where it’s explained exactly why the switch was made. Even if you don’t care for Rust it’s pretty clear that this was done with more purpose than just “Ooo let’s make it in Rust for fun”
And even if it was for fun, that would still be valid. The project is run by volunteers. If they don’t have fun, they stop doing it.
Meme language? It was not rewritten in Javascript.
Didn’t this “meme language” ship in a recent Linux kernel?
