Bummer, it's a cool feature, but I don't feel safe relying on undocumented features.

    use regex_automata::{
        meta::Regex,
        util::iter::Searcher,
        Anchored, Input,
    };
    
    #[derive(Clone, Copy, Debug)]
    enum Token {
        Integer,
        Identifier,
        Punctuation,
    }
    
    fn main() {
        let re = Regex::new_many(&[
            r"[0-9]+",
            r"[a-z_]+",
            r"[,.]+",
            r"\s+",
        ]).unwrap();
        let hay = "45 pigeons, 23 cows, 11 spiders";
        let input = Input::new(hay).anchored(Anchored::Yes);
        let mut it = Searcher::new(input).into_matches_iter(|input| {
            Ok(re.search(input))
        }).infallible();
        for m in &mut it {
            let token = match m.pattern().as_usize() {
                0 => Token::Integer,
                1 => Token::Identifier,
                2 => Token::Punctuation,
                3 => continue,
                pid => unreachable!("unrecognized pattern ID: {:?}", pid),
            };
            println!("{:?}: {:?}", token, &hay[m.range()]);
        }
        let remainder = &hay[it.input().get_span()];
        if !remainder.is_empty() {
            println!("did not consume entire haystack");
        }
    }

    $ cargo run
       Compiling regex-scanner v0.1.0 (/home/andrew/tmp/scratch/regex-scanner)
        Finished dev [unoptimized + debuginfo] target(s) in 0.31s
         Running `target/debug/regex-scanner`
    Integer: "45"
    Identifier: "pigeons"
    Punctuation: ","
    Integer: "23"
    Identifier: "cows"
    Punctuation: ","
    Integer: "11"
    Identifier: "spiders"

re.Scanner looks more succinct though...!

To be fair, most things are missing from the official documentation. When I learned kotlin, I read through their official docs, and knew about most language features in a day. When I learned python, I constantly got surprised by things I hadn't seen come up in the docs. For instance decorators was (still is?) not mentioned at all in the official tutorial.

There now -- https://docs.python.org/3/library/re.html#match-objects

This prevents a ton of import problems, albeit for the price of more verbose typing, especially since you don't have completion on dotted path.

It is my favorite way of running my projects.

Unfortunalty it means you can't use "-m pdb", and that's a big loss.

Not sure what you mean -- sqlite3 is the SQLite CLI.

www='python -m http.server'

I suspect it's related to relative path resource but never figured it out.

    alias json-format="python -m json.tool | pygmentize -l javascript"

> Seth pointed out this is useful if you are on Windows and don't have the gzip utility installed.

Okay, so instead of installing gzip (or just using the decompressors that aren't the official gzip utility but that do support the format and already ship with Windows by default[1]), you install Python...?

Even if the premise weren't muddy from the start, there is a language runtime and ubiquitous cross-platform API already available on all major desktops that has a really good, industrial strength sandbox/containerization strategy that more than adequately mitigates the security issues raised here so you can e.g. rot13 without fear all day to your delight: the browser.

1. <https://news.ycombinator.com/item?id=36099528>

Seems to be a quite rare vector for exploitation.

Sure, on a multiuser system I might trick some other user into running such a command in /tmp and prepare that directory accordingly, but other vectors seem more esoteric.