Tracking Issue for `Iterator::exactly_one` and `Iterator::collect_array`

[jdonszelmann]

Feature gate: #![feature(exact_length_collection)]

This is a tracking issue for exact length collection, concerning originally one but after discussion two new APIs on iterators:

• exactly_one() to collect the one and only element from an iterator
• collect_array() to collect an iterator into an array of an exact predetermined length.

Public API

// trait Iterator

// note: unlike itertools, returns an Option, not a result as per ACP
fn exactly_one(self) -> Option<Self::Item>
where
    Self: Sized;
fn collect_array<const N: usize>(self) -> Option<[Self::Item; N]>
where
    Self: Sized;

Steps / History

(Remember to update the S-tracking-* label when checking boxes.)

• ACP: only on iterators libs-team#676
• Implementation: implement Iterator::{exactly_one, collect_array} #149270
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• None yet.

Footnotes

1. https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html ↩

[Paladynee]

#t-libs > Implementing `Iterator::collect::<Option<[T; N]>>`in stdlib @ 💬