Here's an example for the specific case where the .map() operations are nested. The problem it solves is how to propagate a failure from the innermost closure while avoiding using .unwrap() …

Jan 26, 2022 · As Lukas suggested, the map_or method can also be used. Note that arguments passed to are eagerly evaluated, so if performance is critical, you might want to consider …

203 Rust likes to be more general than that; mapping is done over iterators, rather than over solely vectors or slices. A couple of demonstrations:

Nov 4, 2021 · If, on the other hand, I use an async block, the closure would return impl Future<Output = Option<_>> which is not allowed because Option::and_then only allows …

Jun 12, 2020 · I am trying to get ages of all Person who has some second name. I was able to do it using filter and map separately as below, But I am wondering if we can use filter_map in rust. …

Aug 17, 2017 · Rust is preventing you from mutating the map while you are iterating over it. In most languages this is allowed, but often the behaviour is not well-defined, and removal of the …

Apr 2, 2016 · 16 You can implement these iterators yourself. See how filter and map are implemented in the standard library. map_ok implementation: rust

Jan 2, 2022 · 8 map_err is returning a Result<i64, ParsePosNonzeroError> but you're trying to affect it to x, which you declared as an i64 variable. You need to add a ? so that an Err result …

Oct 1, 2020 · How to map over only the Some () values in an iterator? Asked 5 years ago Modified 5 years ago Viewed 7k times

Sep 20, 2022 · map_or takes a value, this means the "or" has to be evaluated before the method is even called, that is in a.map_or(b, fn) Rust has to first fully evaluate a and b before it can …