Function core::array::try_from_fn
source · pub fn try_from_fn<R, const N: usize, F>(
cb: F
) -> <<R as Try>::Residual as Residual<[R::Output; N]>>::TryType
🔬This is a nightly-only experimental API. (
array_try_from_fn
#89379)Expand description
Creates an array [T; N]
where each fallible array element T
is returned by the cb
call.
Unlike from_fn
, where the element creation can’t fail, this version will return an error
if any element creation was unsuccessful.
The return type of this function depends on the return type of the closure.
If you return Result<T, E>
from the closure, you’ll get a Result<[T; N], E>
.
If you return Option<T>
from the closure, you’ll get an Option<[T; N]>
.
§Arguments
cb
: Callback where the passed argument is the current array index.
§Example
#![feature(array_try_from_fn)]
let array: Result<[u8; 5], _> = std::array::try_from_fn(|i| i.try_into());
assert_eq!(array, Ok([0, 1, 2, 3, 4]));
let array: Result<[i8; 200], _> = std::array::try_from_fn(|i| i.try_into());
assert!(array.is_err());
let array: Option<[_; 4]> = std::array::try_from_fn(|i| i.checked_add(100));
assert_eq!(array, Some([100, 101, 102, 103]));
let array: Option<[_; 4]> = std::array::try_from_fn(|i| i.checked_sub(100));
assert_eq!(array, None);
Run