I think its worth mentioning that rust has the gold standard argument parsing library now: https://clap.rs

That library is used by most(?) rust cli tools, so they all have a similar feel. In addition, there is a library built on top of clap called struct-opt that makes bringing up a new cli exceedingly easy: https://docs.rs/structopt/0.2.15/structopt/

Seriously, checkout struct-opts page even if you don't know any rust. I think their demonstration on the front page summarizes a lot of things I like about idiomatic rust.