opaque data types

[Stephen J. Turnbull]

Ted Zlatanov writes:

 > Generally, I love how Lisp balances readability, accessibility, and
 > power by limiting itself to data structures that are not opaque.  The
 > exceptions to that rule are the interesting edge cases :)

You mean exceptions like plists?

 > (By contrast, Java

 > On Fri, 07 Jun 2013 12:07:44 +0900 "Stephen J. Turnbull" <address@hidden> 
 > wrote: 
ou 

 > makes data structures and objects impenetrable by
 > default and requires nasty tricks to get introspection.

Introspection is a question of API design.  The Lisp that you love is
a trivial design.  There's one data structure: the cons.
Introspection is provided by the access functions and the repl.

On the other hand, you seem to like hash tables.  How do you
introspect the number of buckets and the hash function in Emacs?
Another example: XEmacs takes you half-way there.  It displays the
number of buckets in the un(read)able print representation.