`let` defines a new binding, as opposed to changing the value of an existing binding. You can't remove `let` to keep only `=` because it has a different use cas

`let` defines a new binding, as opposed to changing the value of an existing binding. You can't remove `let` to keep only `=` because it has a different use case. Not indicating the type is idiomatic in Rust, but you can annotate it: let commit_message: String = repo.head().peel_to_commit().ok()?.message()?.into(); Here this is useful to specify the type `into` should convert to. However, if rewritten as: let commit_message = repo.head().peel_to_commit().ok()?.message()?.to_string(); Then it is useless because we're already specifying the type of the variable by using `to_string`. Note that IDEs are displaying type hints anyway (without you having to type them), so you don't have to suffer if walking through a codebase where people are annotating their types too little for comfort