The mathematical abstraction of irrational. That is, when I think of a real number abstractly, it includes irrationals. The fact that I have to use a representation that doesn't include irrationals doesn't mean I give up the abstract idea of reals. <div class="gmail_quote">On Sat, Nov 19, 2011 at 10:27 AM, Robby Findler <<a href="mailto:robby@eecs.northwestern.edu">robby@eecs.northwestern.edu</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"> <div class="im">On Sat, Nov 19, 2011 at 9:54 AM, Doug Williams <<a href="mailto:m.douglas.williams@gmail.com">m.douglas.williams@gmail.com</a>> wrote: > I would keep finite? for the semantics associated with the name even if it > is just a renaming of rational?. Particularly since you can't just use (not > (infinite? x)) when NaNs are a possibility. [I personally don't like using > rational? for an abstraction that includes irrational numbers.] </div>Forgive me for being dense, but IIUC, aren't there no irrational numbers in Racket? Or, put another way, which class of numbers do you find useful to single out using rational?? Robby </blockquote></div>