3 ms·

IMO the issue here is with the question mark operator. If the Rust question mark operator was more like Kotlin's this wouldn't be an issue.

• fanf2 6y ago
  It looks like Kotlin uses ? for nullable types, which isn’t really anything to do with Rust’s ? for short-cut error handling. https://kotlinlang.org/docs/reference/keyword-reference.html https://kotlinlang.org/docs/reference/keyword-reference.html You can also use ? with Option: fn process_item(input: Option<Item>) -> Option<Item> { let item = input?; Some(item + 3) }
  • masklinn 6y ago
    I'm guessing they're referring the `?.` "safe calls" operator[0-] which essentially acts as a mix of `map` and `andThen` except only for property accesses and method calls, and can be combined with `let` for a more general map-like behaviour. [0] where many conceive of the operation as `?` being a modifying operator to `.`
  • pirocks 6y ago
    In kotlin your example would be: fun process_item(input: Item?) -> Item? { input?.plus(3) } This would have to be modified in rust to apply to both error and option types, as well as working on stuff other than the . operator, but I think it could be made to work. The main difference is that the ?. operator in kotlin works at the expression level, instead of the function level.