I definitely like the ternary version, but to my original point I think people make too big a deal about it. With respect to map/filter/groupBy, I rarely find that solutions are clearer when expressed as chains of iterator combinators like these rather than a single for loop, especially when you're dealing with multiple collections and dealing with errors (short-circuiting). I'm writing a lot of Rust lately, and I definitely find myself dealing with this a lot in practice.