EGO -- The architecture

The Self-like object-oriented programming language EGO is implemented
using a primitive (Level Zero) interpreter written in Common Lisp.
All EGO objects are represented as Common Lisp structures.  EGO objects
with primitive values (integers, booleans, symbols, and selectors) use
the "value" field of this structure to house Common Lisp objects
that in turn represent these values at the primitive level.  The ego-instance
structure also houses a hashtable, which is used to store all of
an instance's "ego level" slots.   The store field is use for the
instance's "indexable part".   A separate field is also used to to
house the object's parent list.