[racket-dev] nan?, infinite? and regular-real? [Was: Latest Plot Package]

From: Stephen Bloch (bloch at adelphi.edu)
Date: Fri Nov 18 15:35:26 EST 2011

On Nov 18, 2011, at 2:34 PM, "Neil Toronto" <neil.toronto at gmail.com> wrote:

> ... I'd like to add exact-round, exact-floor, exact-truncate and exact-ceiling. I rarely need to chop off fractional parts without also making the result exact.

That might be convenient, but it's philosophically dubious.  Consider rounding the inexact value 5.49 plus or minus .05.  Saying the answer is "exactly" 5 is claiming more certainty than you actually have: it might be 6.

Stephen Bloch
sbloch at adelphi.edu

Posted on the dev mailing list.