John Cowan wrote:

> Sudarshan S Chawathe scripsit:

> >   * Are comparators that reflect a partial ordering of objects
> >     permitted?  The definition of ordering predicate seems to permit it.
>
> The programmer responsibilities rule that out.  If a < b, then it's
> forbidden for b < a, by the definition of mathematical asymmetry.

I think my earlier comment about partial orders was a bit vague.
Let me try again with a more concrete situation.  Are the following
allowed by the SRFI?

  (make-comparator (lambda args #t)
  		   equal?
		   (lambda args #f)
		   #f)

  (make-comparator exact-integer?
  		   =
		   (lambda (i j)
                     (and (even? i)
                          (even? j)
                          (< i j)))
		   number-hash)

The main question here is whether the SRFI requires comparators to
totally order all elements accepted by their type-test predicates, or
whether it is OK if none (1st example) or only some (2nd) are ordered.

Regards,

-chaw