A few questions

[Adam D. Ruppe]

I started a not null struct for phobos but then had to
move, added another job, and other real life stuff
that meant I haven't finished it yet.

Fairly usable though. Look for struct NotNull:

https://github.com/adamdruppe/phobos/blob/0c97414bb4aa3c748caa42948ffec25f8a291300/std/typecons.d

(also a pull request, but for some reason, my changes to
never updated here, so the pull request is out of date
and temporarily closed

https://github.com/D-Programming-Language/phobos/pull/477 )