Hello and welcome to another issue of This Week in Rust! Rust is a systems language pursuing the trifecta: safety, concurrency, and speed. This is a weekly summary of its progress and community. Want something mentioned? Tweet us at @ThisWeekInRust or send us a pull request. Want to get involved? We love contributions.

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News & Blog Posts

Crate of the Week

This week's crate is multi_try, a crate to simplify working with multiple results. Thanks to Azriel Hoh for the suggestion!

Submit your suggestions and votes for next week!

Call for Participation

Always wanted to contribute to open-source projects but didn't know where to start? Every week we highlight some tasks from the Rust community for you to pick and get started!

Some of these tasks may also have mentors available, visit the task page for more information.

If you are a Rust project owner and are looking for contributors, please submit tasks here.

195 pull requests were merged in the last week

Approved RFCs

Changes to Rust follow the Rust RFC (request for comments) process. These are the RFCs that were approved for implementation this week:

No RFCs were approved this week.

Every week the team announces the 'final comment period' for RFCs and key PRs which are reaching a decision. Express your opinions now.

No RFCs are currently in final comment period.

New RFCs

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Quote of the Week

And again, we have two quotes for the week:

Can you eli5 why TryFrom and TryInto matters, and why it’s been stuck for so long ? (the RFC seems to be 3 years old) If you stabilise Try{From,Into}, you also want implementations of the types in std. So you want things like impl TryFrom for u16. But that requires an error type, and that was (I believe) the problem. u8 to u16 cannot fail, so you want the error type to be !. Except using ! as a type isn’t stable yet. So use a placeholder enum! But that means that once ! is stabilised, we’ve got this Infallible type kicking around that is redundant. So change it? But that would be breaking. So make the two isomorphic? Woah, woah, hold on there, this is starting to get crazy… new person bursts into the room “Hey, should ! automatically implement all traits, or not?” “Yes!” “No!” “Yes, and so should all variant-less enums!” Everyone in the room is shouting, and the curtains spontaneously catching fire. In the corner, the person who proposed Try{From,Into} sits, sobbing. It was supposed to all be so simple… but this damn ! thing is just ruining everything. … That’s not what happened, but it’s more entertaining than just saying “many people were unsure exactly what to do about the ! situation, which turned out to be more complicated than expected”.

– /u/Quxxy on reddit

What is the ! type? The never type for computations that don’t resolve to a value. It’s named after its stabilization date.

– /u/LousyBeggar on reddit

Thanks to runiq and StyMaar for the suggestions!

Please submit your quotes for next week!

This Week in Rust is edited by: nasa42, llogiq, and Flavsditz.