equality predicates (was Re: [plt-scheme] fractions and decimals)

From: Robert Bruce Findler (robby at cs.uchicago.edu)
Date: Tue Jan 28 10:19:54 EST 2003

Actually, I think that integer? is, but positive? isn't:

  Welcome to MzScheme version 203.2, Copyright (c) 1995-2003 PLT
  > (integer? #f)
  > (positive? #f)
  positive?: expects argument of type <real number>; given #f


At Tue, 28 Jan 2003 10:15:46 -0500 (EST), Doug Orleans wrote:
>   For list-related administrative tasks:
>   http://list.cs.brown.edu/mailman/listinfo/plt-scheme
> Stephen Bloch writes:
>  > Now THAT's peculiar: I was under the impression that "equal?" was 
>  > implied by all the other equality predicates.
> It is, depending on your definition of equality predicate.  :)
> The weird thing about `=' (and `string=?' et al) is that it isn't a
> general predicate; `(= "foo" "bar")' doesn't return false, it raises
> an error.  Similarly, `integer?' isn't a type predicate, because it's
> only defined on numbers.
> --dougo at ccs.neu.edu

Posted on the users mailing list.