CLI tools hidden in the Python standard library(til.simonwillison.net)

    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"

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

    $ python -m fire random uniform 0 1
    0.5502786602920726

    $ python -m fire math radians 180
    3.141592653589793

    $ python -m fire math e
    2.718281828459045

    $ python -m fire random