Cargo: predictable dependency management
Something that I'm surprised this page doesn't talk about, and which is very important considering the recent hubbub over left-pad, is that any dependency you get on Cargo can be relied upon to continue to exist forever (well, as long as the crates.io site still exists, but if that goes away so does the Cargo index). The reason is because you can't ever remove a published version of your crate from crates.io. You can yank a version, which tells Cargo not to allow any projects to form new dependencies on that version, but the version isn't actually deleted and any projects that have existing dependencies on that version will continue to be allowed to use it. This is documented at http://doc.crates.io/crates-io.html#cargo-yank.