Use `_` in crate names

[sffc]

We are using hyphens in package names, but underscores pretty much everywhere else:

• File names
• Crate names
• Module names
• Function names

I don't understand why we don't use underscores in package names, too. There are lots of Rust packages that use underscores, like serde_json. This would eliminate the oddness that you put "icu-locale" in Cargo.toml, but then when you use it in code, you need to write "icu_locale".

[zbraniecki]

That's one of the Great Unresolved Debates in Rust:

• https://users.rust-lang.org/t/is-it-good-practice-to-call-crates-hello-world-hello-world-or-does-it-not-matter/6114
• https://twitter.com/nick_r_cameron/status/966739599052570624?lang=en
• https://rust-lang.github.io/rfcs/0940-hyphens-considered-harmful.html
• Accept hyphen in crate name in place of underscore rust-lang/cargo#2775
• https://www.reddit.com/r/rust/comments/7x2ls9/consistentify_hyphen_usage_on_cratesio/
• https://www.reddit.com/r/rust/comments/8sezkm/where_are_the_rules_for_creating_valid_rust/

This is exactly the kind of thing I look at Rust leadership to make a call on.

@Manishearth - what's the latest?

[Manishearth]

I'm not sure if there's ecosystem-wide agreement on what to do, but my impression is that people prefer to use dashes. There are open bugs to make crates.io, cargo, and docs.rs more agnostic to dashes-vs-underscores (you already cannot publish crates that only differ on dashes vs underscores). Dashes look nicer so folks tend to use them more.

[zbraniecki]

Consensus is to:

• switch to _ for crate names to reduce confusion between names and imports.
• rename pluralrules to plurals and unicodeset to uniset.

[Manishearth]

switch to _ for crate names to reduce confusion between names and imports.

Is there really confusion? - doesn't work in imports so it's obvious it needs to be _, and when I type a crate I almost always try - first. If anything it's confusing when the crate name contains _ because most crates tend to use -.

[zbraniecki]

Is there really confusion?

If the choice is between always use _ and use _ in X, and use - in Y then the former is more consistent and simpler, right?

If Rust settled the dispute and decided to go for - in crate names, I believe we would follow. With Rust Core Group not making any decisions and crates doing both, it becomes an arbitrary choice and we'd prefer to go for what is simpler for us if it's wild west of namings anyway.

How strongly you feel about - in crate names? Would you like us to postpone renames and discuss? Would you be able to provide any justification beyond it looks better that counters the its consistent?

[Manishearth]

If Rust settled the dispute and decided to go for - in crate names, I believe we would follow.

The community has largely decided on -, with _ being used more in older crates, but it's not 100% decided.

Here are the counts of - vs _:

[16:49:22] मanishearth@noether ~/sand/crates.io-index ^_^ 
$ find . -type f | sed "s/.*\///g" | tr -d -c "_" | wc -c
10901
[16:49:45] मanishearth@noether ~/sand/crates.io-index ^_^ 
$ find . -type f | sed "s/.*\///g" | tr -d -c "-" | wc -c
24828

Would you be able to provide any justification beyond it looks better that counters the its consistent?

Yes, because - is more common than _ except for older crates and some holdouts, people typically try for - first, and when that doesn't work they try the other one.

Some namespacing proposals also involve specially blessing -, though they are unlikely to pass.