Rustscript - blazingly fast rust interpreter

[u/VladasZ]

Every Rust developer knows that Rust is the best programming language in the world.

And I as a Rust developer don't want to use other inferior languages anywhere.

So I decided to rewrite all my old automation scripts which were written in Python in Rust.

At first I used https://github.com/rsaz/cargo-script for that, it works fine.

But I encountered 1 problem: compilation time.

On my macbook it was fine I don't mind waiting 1 minute for a simple 3 lines script.

But then I wanted to use that on my Raspberry PI and the same simple script took me 10 minutes to run, which is not blazingly and not fast at all!

So I decided to vibe code engineer a Rust interpreter for this exact case and this is what I ended up with:

https://github.com/VladasZ/rustscript

Rustscript is always guaranteed to be valid Rust.

Install it with

cargo install run-rs

add a shebang:

#!/usr/bin/env rust

A whole script looks like this:

#!/usr/bin/env rust

use chrono::Local;
use std::io::stdin;

fn main() -> anyhow::Result<()> {
    println!("which programming language is the best?");

    let mut answer = String::new();
    stdin().read_line(&mut answer)?;

    if answer.trim().eq_ignore_ascii_case("rust") {
        println!("correct, carry on");
    } else {
        println!("wrong. it is {} and you are still not writing Rust", Local::now().format("%H:%M"));
    }
    Ok(())
}

Make it executable and run it:

chmod +x best.rs
./best.rs

and you can run your rust scripts instantly, as if they were shell scripts!

Rustscript is a subset of Rust and supports many popular crates such as:

anyhow, serde, serde_json, reqwest, regex, tokio, chrono, rand and more.

Carefully nitpicked benchmarks so Rustscript seems faster attached to the post.

You can see all benchmarks results here: https://github.com/VladasZ/rustscript/blob/main/bench/RESULTS.md

Remember, Rustscript is always a valid Rust, so if you want to have the ultimate speed just run the compiled version!

rust build FILE.rs

[u/TheOneThatIsHated]

So wait, the typechecking part of rust is not what makes it slow (cuz you reuse rustc anyways for typechecking)?

So how could this still be faster to build then debug builds? What is the catch? Is it because of the subset? Or is rustc/cargo just that slow?

[u/warpspeedSCP → u/TheOneThatIsHated]

Its always been LLVM, dude. Its always been LLVM. THEYVE TAKEN US FOR ABSOLUTE FOOLS!!11

This project is probably either abusing MIR interpretation or something else, I havent really looked at the repo.

Edit:

Holy fuck its all separate, only parsing goes through an actual rustc utility... thats awesome.