Comment by pjmlp

It was the research into systems like Xerox Cedar, among others, that turned me into a believer of systems programming with automatic resource management languages.

Most of these systems failed not due to technical limitations, rather by poor management decisions that ended up killing their adoption.

Likewise in the UNIX world, my favourite ones are the ones that went out of their way to not be yet another UNIX V6 clone with X, like IRIX, NeWS and NeXTSTEP.