ACP: Implement `TryFromIterator<T>` trait to compliment `FromIterator<T>` trait.

[stifskere]

Proposal

Problem statement

I want to compliment the FromIterator<T> trait with a TryFromIterator<T> trait as that would basically be a fallible alternative to FromIterator<T>, it would be the same but the trait would have an Error field and the function would return a Result<R, Self::Error>.

Motivating examples or use cases

A use case I recently had was this one, basically the use cases for his would be making iterator implementations safer.

Solution sketch

My solution for this ACP is basically this one

pub trait TryFromIterator<T>: Sized {
    type Error;

    fn try_from_iter<I: IntoIterator<Item = T>>(iter: I) -> Result<Self, Self::Error>;
}

Or something similar

Alternatives

Probably making this a crate in crates.io doesn't make much sense, the alternatives to this is implementing it per project.

Links and related work

This thread literally solves the problem.

What happens now?

This issue contains an API change proposal (or ACP) and is part of the libs-api team feature lifecycle. Once this issue is filed, the libs-api team will review open proposals as capability becomes available. Current response times do not have a clear estimate, but may be up to several months.

Possible responses

The libs team may respond in various different ways. First, the team will consider the problem (this doesn't require any concrete solution or alternatives to have been proposed):

• We think this problem seems worth solving, and the standard library might be the right place to solve it.
• We think that this probably doesn't belong in the standard library.

Second, if there's a concrete solution:

• We think this specific solution looks roughly right, approved, you or someone else should implement this. (Further review will still happen on the subsequent implementation PR.)
• We're not sure this is the right solution, and the alternatives or other materials don't give us enough information to be sure about that. Here are some questions we have that aren't answered, or rough ideas about alternatives we'd want to see discussed.