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Re: standard-type-classes

"Question.  Should the same object have the same class (with the same
name) in all standard Common Lisp systems?  What do we do about the
float set which has several different classes that may be collapsed.
This seems like a reason to omit (some) implementation dependent

There are a number of examples where it seems clear that we want to make
no such requirement. For example, we don't want to require that
implementations *not* use the class system to implement stream classes,
e.g. (class-of (make-two-way-stream a b)) should not be required to be
the class STREAM but merely STREAM or some subclass of STREAM.  I think
the floating point classes are in the same category, i.e., they are
"implementation-dependent classes" and code that discriminates on them
is allowed and implementation-dependent.