The damn documentation doesn't even say what the type of each property is! Nor the return types of built-in functions and methods. Apparently I have to freaking guess. You've got to be kidding me.
Eric Raymond may call them “bondage-and-discipline languages” http://www.catb.org/~esr/jargon/html/B/bondage-and-discipline-language.html but languages like Rust don't let anyone get away with this nonsense. Not even the authors of the standard library.