If you're familiar with say, `Vec<u8>` and `[u8]`, `String` and `str` are basically the same except they are contractually valid UTF bytes. So just like you can `push` and `extend` to a `Vec`, you can do the same to a `String`.

With regard to generic type parameters, if you want to code in Java or Go style, you can use dynamic dispatch trait objects to remove type parameters.

I've found that sometimes this doesn't happen automatically (at least when passing as an argument; maybe not when calling methods). i.e., you have to explicitly call .as_str() in some situations. Even as someone who's comfortable with the String/&str distinction and moderately familiar with Rust, it's not clear to me where this is and isn't necessary. The compiler just tells me when I make the wrong guess.

Any time you have a &String reference, it triggers coercion to &str.

    let my_str = "Hello".to_owned();
    match &my_str {
        "Hello" => (),
        _ => ()
    }