The Haiku operating system, which is a modern, open source re-implementation of BeOS from the 1990's, has an interesting software packaging system. Much like Debian's .deb or RedHat's .rpm files, Haiku's .hpkg files include the files, description of the software, and dependencies. Like it's Linux cousins, it also ensures that the dependencies are met, installing the dependencies if not already installed and available in the repository.

What sets Haiku's package manager apart is two things: Each file in the package is mounted as a read-only file into the file system, which ensures security; and the boot manager is aware of the state of the packing system, allowing the user to reboot and start the operating system as it was in a prior state.

Since each file is mounted from the package into the file system, it cannot be changed, either by the user (intentionally, or accidentally), or by a mis-behaving application. The only way to change the file is to install a different version, or to uninstall it completely. There is a downside to this though, it does make porting some applications tricky.