Ethos’ Distributed Types

Programming languages have long incorporated type safety, increasing their abstraction level and thus aiding programmers. Type safety eliminates whole classes of bugs, avoiding the tedious and error-prone search for these bugs. Type-related bugs are particularly dangerous and often result in security holes because they violate programmer expectations. Despite its benefits, type safety protections traditionally end at the process boundary. We describe the deep integration of type safety in Ethos, a clean-slate operating system, which ensures that communication and files conform to their expected type. Ethos types are languageand runtime-agnostic, and incorporate a new mechanism for automatically creating type identifiers. We explore the impact of type safety on type descriptions, filesystem structure, scripting languages, file streaming, and application programming.