Syntax for matching on a collection element is not obvious

[mdinger]

The documentation should document how [] changes inside a match as opposed to outside of one. A quick browsing of the guides didn't find this noted anywhere:

fn main() {
    let array = ["a", "b"]; // `[]` denotes `array`
    let v = vec!["match_this", "1"];

    match v {
    //    ^ Change `v` to `v.as_slice()` to make this work. Hard to discover...

        // How does this work though? It appears like this is matching a slice
        // against an array and succeeding. It is not obvious that `[]` inside a
        // match is `slice` syntax and not `array` syntax

        // Now `[]` denotes slice...
        ["match_this", a] => println!("{}", a),
        _ => {},
    }
}