What is Expressiveness in a Computer Language

[Torben Ægidius Mogensen]

Raffael Cavallaro <raffaelcavallaro at pas-d'espam-s'il-vous-plait-mac.com> writes:

> On 2006-06-14 16:36:52 -0400, Pascal Bourguignon <pjb at informatimago.com> said:
> 
> > In lisp, all lists are homogenous: lists of T.
> 
> CL-USER 123 > (loop for elt in (list #\c 1 2.0d0 (/ 2 3)) collect
> (type-of elt))
> (CHARACTER FIXNUM DOUBLE-FLOAT RATIO)
> 
> i.e., "heterogenous" in the common lisp sense: having different
> dynamic types, not in the H-M sense in which all lisp values are of
> the single union type T.

What's the difference?  Dynamically types values _are_ all members of
a single tagged union type.  The main difference is that the tages
aren't always visible and that there are only a fixed, predefined
number of them.

        Torben