> A lack of default arguments, a lack of basic arity overloading, a lack of variadic generics, all make me not want to write Rust.

I'm not sure how serious this is, TBH? I mean, Rust does have macro syntax that supports all of these things (as seen e.g. in println!() and format!() ), and there are pretty solid engineering reasons to avoid those features within the basic workings of the language. I'm pretty sure most Rustaceans would argue that Rust is quite probably Doing the Right Thing here.