> It's also terrible for security. The security angle is interesting. The thing about independent processes is that we're relying on the OS to provide a wall

> It's also terrible for security. The security angle is interesting. The thing about independent processes is that we're relying on the OS to provide a wall around each process to limit it's impact by default. Maybe a better approach would to be include something like chroot/containerization for execution of closures within the language? Ie, if program 'A' receives data from program 'B', it can evaluate that data in a sandbox with limited permissions (IO limitations like no networking, or CPU resource limitations and time limits) and receive exceptions if the closure tries to exceed it's permissions. That could fit in pretty cleanly with Common Lisp's condition system. A con of this though: you could argue that it really breaks encapsulation; it's bad enough when different parts of a large program become too closely coupled - allowing different applications to depend on the internal state of each other could be a nightmare.