Since I'm now actively interested in #Rust, I'll take the liberty to sometimes post n00b questions.

(Because a) this may well help others, and b) I firmly believe asking seemingly innocent questions along the way is about the best way to learn.)

One: Why do we have vec! but not str!? We've got .to_string() and String::from(). Presumably, a cleverly built macro would pick one wisely, and reading str!(...) would be very natural for someone who's used to vec!(...). So, there must be a reason, but I can't comprehend it.

Two: Is there a way to install and pre-build dependencies? I want a build Docker container for my unit tests. Ideally, I'll update it nightly, so that Github actions that run my tests would just docker pull from ghrc the most recent { Rust toolchain + basic pre-cloned and pre-built } modules.

For this "two" to work I need my Dockerfile with the build container to do something like cargo install (?) and cargo prebuild (?) for a bunch of [dependencies] from multiple Cargo.toml files. I've tried that, and Cargo gives me trouble, primarily because it can't "just" download & install packages without the "main binary". I dare say, npm install has never given me this vibe as long as package.json is there. So there absolutely must be something I'm doing wrong.

Hints, anyone? Thanks in advance!

PS: I'm a two-spaces indent guy (and 120 characters line width). Is this totally frowned upon, or would a non-insignificant share of Rust lovers be okay with this?