Symbols as Namespaces in Common Lisp

In this paper, we propose to extend Common Lisp’s fundamental symbol data type to act as a namespace for other symbols, thus forming a hierarchy of symbols containing symbols and so on recursively. We show how it is possible to retrofit the existing Common Lisp package system on top of this new capability of symbols in order to maintain compatibility to the Common Lisp standard. We present the rationale and the major design choices behind this effort along with some possible use cases and we describe an implementation of the feature on a modified version of Armed Bear Common Lisp (ABCL).