DEFVST

[Edward Barton <EB at MIT-AI>]

What is the proper way to make DEFVST constructions intelligible
to the compiler but unavailable at runtime?

(eval-when (compile)
  (defvst barf a b c))

(defun foo () (cons-a-barf a 1 b 2 c 3))

seems reasonable, but this causes the result of (FOO) to produce
a hunk whose struct-typep is nil and which contains "UNBOUND"
for at least one component.  (where FOO is loaded compiled)