[r6rs-discuss] Re: [Formal] formal comment (ports, characters, strings, Unicode)

From: William D Clinger <will>
Date: Tue Mar 20 15:39:07 2007

I am posting this as an individual member of the Scheme
community. I am not speaking for the R6RS editors, and
this message should not be confused with the editors'
eventual formal response.

I wrote:

> That is an equivalence predicate, and it is definable in
> R5.92 Scheme, but char<=? does not define a total ordering
> with respect to that predicate.

Well, actually it does. Let's try that again:

    (define (klepto:char-equiv? c1 c2)
      (let ((i1 (char->integer c1))
            (i2 (char->integer c2)))
        (= (remainder i1 200) (remainder i2 200))))

That is an equivalence predicate, and it is definable in
R5.92 Scheme, but char<=? does not define a total ordering
with respect to that predicate.

Will
Received on Tue Mar 20 2007 - 15:38:53 UTC