[steveklabnik]

Packages are made up of modules, and modules can have global state. But doing so directly is unsafe, specifically because it can introduce a data race. Rust also does not have “life before main”, so it doesn’t get used in the same way as languages that do. I’m not sure if Go does?

[bbatha]

Even if its not just "mutable" state there are a lot of undesirable situations for multiple package imports in rust:

1. Singletonish things like global allocators, rayon-core, etc

2. You may have made a package static safe to mutate with a mutex, but it could be a bad thing to have different versions of that mutex.

3. Compile time computed tables (unicode table, perfect hashes, etc) could be imported multiple times ballooning the binary.

4. ABI/type compatibility with any reexported types

[steveklabnik]

Oh totally. Thanks for listing those out.

[dilap]

(I replied but the reply vanished. If it reappears, apologies for the dup.)

Yeah, go has a magic function `func init()` which gets called before main. (You can actually have as many init's as you want, and they all get called.)

Probably evil, though so far it hasn't hurt me in the same way as, e.g., c++ constructors have. Maybe because it's more explicit and thus you're less likely to use it in practice.

[steveklabnik]

Cool, thanks!