As another poster said, None is in the prelude. It’s been explicitly imported, just… implicitly so. Other than that, Rust places strong emphasis on function si

As another poster said, None is in the prelude. It’s been explicitly imported, just… implicitly so. Other than that, Rust places strong emphasis on function signatures. They override everything else, such as inferred return types from the function body. This is to ease composition and reading (as far as I remember). That is to say, in Rust it is quite natural to refer back to the function definition, potentially to let it do inference heavy lifting, or work with the question mark operator. It doesn’t feel the wrong way.