Re: A value for "nothing"

[Matt Wette]

Is it reasonable to expect that if a value can be assigned to a variable
then a predicate exists to test for that value type?  So, if

  (define a (if #f #f))

does not signal an error then there should be a predicate to indicate the
value associated with a is unspecified?

If the define allowed in RnRS?  I don't believe there is a predicate to
test for this. (I could be wrong.)

Comments?

Matt