You're describing a chroot jail. key there is "process". Dealing with processes permissions is the OS's job. A if a language wants to deal in library's securit

You're describing a chroot jail. key there is "process". Dealing with processes permissions is the OS's job. A if a language wants to deal in library's security it should strive to make static analysis possible. Eg: the language guarantees that network and filesystem calls can only be done with a single function, statically so I can audit that leftpad indeed doesn't make network calls .