Lisp Data Type Coding
Since there are several Lisp data types that can be denoted by a
pointer, there must be some way to distinguish them. There are
several ways to do this.
- Each datum can contain a type field or tag
that tells the type of the
- Each pointer can contain a type field or tag that tells the type of the
datum pointed to.
- Each pointer can implicitly contain the type by keeping only one type
of data on a given page of computer memory; the type is then found by
table lookup using the high-order bits of the pointer address.