是否可以将Option< Result< T,E>到结果<选项< T>,E>.不使用火柴? [英] Is it possible to convert Option<Result<T, E>> to a Result<Option<T>, E> without using match?
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问题描述
我首先想到的是map
Option
,但是我不能从闭包内部使用try!
. match
语句看起来不必要,但是我不知道如何简化它.
My first thought is to map
the Option
, but I can't use try!
from inside of the closure. The match
statement looks unnecessary, but I can't figure out how to simplify it.
fn example<T, E>(val: Option<Result<T, E>>) -> Result<Option<T>, E> {
Ok(match val {
Some(v) => Some(v?),
None => None
})
}
推荐答案
在Rust 1.33中, transpose()
是稳定的,因此您可以调用它:
In Rust 1.33, transpose()
is stable, so you can just call it:
fn main() {
let x: Result<Option<i32>, ()> = Ok(Some(5));
let y: Option<Result<i32, ()>> = Some(Ok(5));
assert_eq!(x, y.transpose());
}
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