I see. My apologies for being so critical. I agree that POSIX is incomplete and out of date.
However I do think it is a disaster that people can't break up their shell code into more modular components, and there is no excuse for it.
And I especially do not wish to discourage you from trying to reinvent shell, because someone has to do it, but at minimum I don't see myself moving away from my shell for the better part of a decade. Hopefully at that point Oil's community has matured to the point where I feel comfortable trusting it to be stable and free of any critical privilege escalation bugs.
Good luck!