Adding the ?. null verification

[Etienne via Digitalmars-d]

> Use a maybe monad :
> Maybe(obj).memeber.nested.val
>
> This doesn't require a language construct. Also, if null check are
> pervasive in your code, you probably have a problem somewhere.

There seems to be an implementation here:

https://bitbucket.org/qznc/d-monad/src/5b9d41c611093db74485b017a72473447f8d5595/generic.d?at=master

It doesn't look as good as what you're suggesting,

auto rht = Applicative!Maybe.right(r1, r2);

auto ii42 = Maybe!(Maybe!int).just(i42);

Any idea how that maybe monad would cascade through into the pointer 
accessors?