Don Geddis  <don@geddis.org> wrote:
+---------------
| "P.C." <per.corell@privat.dk> writes:
| > Now my question first came inmind, when I read about "Pure Lisp",
| > where you with 5 primitive functions ;
| > Car Cdr Cons Atom and Eq
| > shuld be able to compose whatever Lisp function,
...
| Hint: you need to decide how to represent numbers at all, using only those
| primitive functions, well before you worry about things like adding them
| together.  What does the number "3" actually look like?  Start with that
| question.
+---------------

For the serious student, this paper is an excellent introduction to the
topic, including a survey of what various implementations have used and
a comparison of execution-time costs of each approach:

  <URL:ftp://ftp.cs.indiana.edu/pub/scheme-repository/doc/pubs/typeinfo.ps.gz>
  Gudeman: "Representing Type Information in Dynamically Typed Languages"


-Rob

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