Rust Result Vs Exception. Maps a Result to Result by applying a function to a contained Ok value leaving an Err value untouched. Rust skips using both especially to prevent issues like null pointer exceptions sensitive data leakages through exceptions and etc.
To let a trait-signature be generic over closures in this way is something which is not yet possible in Rust at the moment but once that is possible do-notation should not be far off. Corrosion is the process of deterioration of materials as a result of chemical electrochemical or other reactions. Result would use FnOnce since it is just run once whereas an iterator would need FnMut since the closure would be executed once for each item.
If you have spent any amount of time learning Rust you quickly become accustomed to Option and Result types.
Applications may also want to parse and inspect errors for example to forward them to exception tracking services or to retry operations when doing so is deemed to be safe. Failure had a semi-official feel to it as a result of being in the rust-lang-nursery namespace but it has recently been deprecated. If you have spent any amount of time learning Rust you quickly become accustomed to Option and Result types. So a ValidateLotteryTicket method should return a result if the ticket is a winner if its not a winner or if the ticket number is invalid.