How about a syntax similar to case, that dispatches based on a member of
an enumeration set, with enumeration-specific error checking?
Specifically, an error would be signaled if the cases are not
exhaustive, or if any clause datum is not a member of the enumeration set.

Also:
(enum-set-min integer-set)
(enum-set-max integer-set)
should read
(enum-set-min enum-set)
(enum-set-max enum-set)

Kevin Wortman