[racket] Question about round

From: Robby Findler (robby at eecs.northwestern.edu)
Date: Fri Sep 30 12:31:47 EDT 2011

Just to clear up one more possible point: the rational? predicate
actually recognizes inexact numbers, eg:

[robby at penghu] ~/git/plt/collects/drracket/private$ racket
Welcome to Racket v5.1.3.9.
> (rational? (sqrt 2))


On Fri, Sep 30, 2011 at 11:18 AM, Mark Engelberg
<mark.engelberg at gmail.com> wrote:
> I'm amazed at how long I've gone with the misconception that:
> Exact Numbers = Integers union Rationals
> Inexact Numbers = Floating Point numbers
> (Frankly, I never really thought much about what infinities were.  I assumed
> they were a separate, distinct type).
> When I saw in the docs for round that it returns an integer, and I was
> getting an inexact number, I was sure it was a mistake.  Thanks for helping
> me straighten out my thinking on this.  I can see how you might want to test
> an inexaxct number for whether it is the floating point approximation of an
> "integer", so that makes sense.  Still seems weird and inconvenient for
> round to give you back an inexact integer rather than an exact one, but I
> can see now how this behavior matches the standard.
> Thanks,
> Mark
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