Ironically, given Rust’s design constraints, providing the kind of composability features the author wants would require adding new syntax. Because control flo

Ironically, given Rust’s design constraints, providing the kind of composability features the author wants would require adding new syntax. Because control flow out of map cannot work as long as map is just a regular function taking a closure. It’s not much different from higher-order functions in JavaScript, really. (Other than the fact that JavaScript has exceptions.)