Interesting, it seems that it allows the exact syntax of shell commands, without using strings.

    // valid rust code and shell code, no strings
    run_cmd!(du -ah . | sort -hr | head -n 10)?;

How does rust parse the statement within run_cmd()? Can rust parse other languages like this?

    run_html!(
COOL
)

Yes! If you are interested in doing front-end in Rust using Wasm, checkout Yew : https://github.com/yewstack/yew The data flow is inspired by React, you’ll feel right at home.