What is memory safety?

This definition of memory safety reminds me of a story of writing a C compiler for LISP machines. As I recall, C pointers were represented in LISP as a tuple of a reference to a buffer, and an index into that buffer. In other words, the exact same solution as used in this article: All pointers carry with them (explicitly, in this case) information about which "derived" pointers are legal.

Good work! The "pointers as capabilities" idea makes it much clearer to me what "memory safety" means. Can we have a similar article about "type safety"? I think many people would benefit from knowing the exact relationship between type safety and memory safety, and whether one is a subset of the other.

> We should think of a pointer as consisting of logically three elements (p,b,e): the legal region is defined by the base b and bounds (or extent) e, and the pointer itself is p.

Everything old is new again. Look up how segmentation works on x86 in 32-bit mode (initially introduced as "protected mode" on 80286).