hyphens and underscores.md

I asked ChatGPT: "Does Rust substitute _ for - in certain instances?"

Reply:

In Rust, hyphens (-) and underscores (_) are not interchangeable in identifiers. Rust enforces consistent naming conventions, particularly with crates and modules, which affects how names with hyphens or underscores are interpreted:

BUT... exceptions and gotchas...

1. Crate Names

In Cargo.toml crates are commonly named with hyphens, like my-crate.

However, within Rust code, hyphens are not allowed in identifiers, so you must use underscores. For example, to import my-crate, you would write:

rust
Copy code
use my_crate::some_function;
Rust automatically translates the hyphen in the crate name to an underscore in code.

3. Feature Flags in Cargo.toml

Feature flags in Cargo.toml can contain hyphens or underscores, and Rust treats them as equivalent. For example, defining a feature as my-feature can also be activated using my_feature.