Rust the language gives these guarantees without the use of the unsafe keyword: * you will not be able to compile undefined behavior * you will not be able to

Rust the language gives these guarantees without the use of the unsafe keyword: * you will not be able to compile undefined behavior * you will not be able to create a data race * a shared reference is read-only * you cannot write past the end of an array There are others, but those are pretty big ones that both guarantees and part of the language itself, independent of stdlib.