Question

For example:

shared_ptr<const shared_ptr<const int> > pp;

is fairly intimidating… whereas

const int ^ const ^ pp;

is instantly reminiscent of the raw pointer equivalent

const int * const * pp;

Answer 1

Everyone missed the real reason 🙂

The nice notation T^ suggests action like a real pointer, which suggests conversions would work the same way. This is not the case. Templates can’t support conversions. For example consider

T^ --> T const^

If you take ^ as *, this will work. However by default for a template:

p<T> --> p<T const>

will not work: templates are not covariant in their arguments. It is not possible to fix this in C++ AFAIK. You can handle that one conversion, but don’t forget the others:

derived --> base
T ** --> T const * const*

just for example. If you want a real type system it has to be designed my mathematicians not compiler writers.