GC/non-GC memory as part of data type?

[Walter Bright]

There are many ways to manage memory, and a non-trivial program will often use 
multiple methods:

1. gc
2. stack
3. static
4. malloc/free
5. reference counting
6. various custom allocators

Using type constructors to create two categories, gc and all the others, in the 
end is not particularly helpful because the number of categories is unbounded 
and reliance on such a system would require supporting all categories.