C and tagged pointers

[PAD Powell[Admin]]

Ah, yes, once again the good old "lets distinguish pointers" strikes

I strongly suggest that "0" be make a "special" pointer under comparison.
First, it can only be used in comparison, and assignment.

This makes life somewhat easier when trying to implement pascal, and have
to deal with the "nil" and unset pointers.

Secondly,  I wonder just how easy it will be to map tagged pointers, and the
infamous C casting of integers to pointers...

Patrick Powell, U. Waterloo