Unspecified?

[Maciek Godek]

Hey all yoh!
Is there any "official" way to check whether or not
a function returns a (specified) value?

As I ran into the problem, I quickly came with a workaround:
(define unspecified (if #f #t))
which allows to define the most basic predicates:
(define (unspecified? x) (eq? x unspecified))
(define (specified? x) (not (unspecified? x)))

but I find it kinda surprising that these are not available
by default in the system.

Best regards
M.