[mikwielgus]

While it's already possible to use index syntax (e.g. v[1]) on Vec due to Deref coercion into slice, it's nevertheless useful to have Index and IndexMut traits implemented if you want to have code that is generic over indexable containers via trait bounds, like in this snippet:

fn increment<C>(container: &mut C, index: usize)
where
    C: std::ops::IndexMut<usize>,
    C::Output: std::ops::AddAssign<i32>,
{
    container[index] += 1;
}

Having these traits is consistent with Rust standard library's Vec, which also implements them.

There are also other collections that could implement Index or IndexMut. If this PR is accepted, I will follow up with implementations for these as well.

[sgued]

Thanks!

I didn't realise std::Vec implemented Index directly. The implementation looks good to me, please change the test and update the changelog.

[sgued]

Why not the following? Using the trait seems correct but I'm curious, this seems more intuitive.

    #[inline]
    fn index(&self, index: I) -> &Self::Output {
        &self.as_slice()[index]
    }

[mikwielgus]

Why not the following? Using the trait seems correct but I'm curious, this seems more intuitive.

    #[inline]
    fn index(&self, index: I) -> &Self::Output {
        &self.as_slice()[index]
    }

I just have a habit of programming defensively when it comes to boilerplatey trait impls, as I ended up with infinitely recursive code a few times due to ambiguities in resolution.

It's probably not needed, but it doesn't make a difference either way.

[sgued]

Thanks, it also lt also makes it closer to the std::Vec implementation which is good.