[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Scheme-reports] More NaN and Infsanity
On Mon, Apr 30, 2012 at 03:41:10AM -0400, John Cowan wrote:
> Peter Bex scripsit:
> > What about (rationalize x y) where x or y are nan or inf?
> > The notation seems to indicate that nan is allowed, since it's
> > "real but not rational". However, that same sentence seems to
> > indicate that rationalizing NaN would be an error.
> Rationalizing infinity makes some sense, but rationalizing NaN does not,
> at least not to me.
What would the result be then? According to the spec, both the
infinities and NaN are rational but not real so infinity is out,
and I don't see any sane value other than infinity (or maybe nan)
as output for, say (rationalize +inf.0 1).
> > On the other hand, R6RS seems to indicate that rationalize is
> > allowed to return +nan.0, see its examples:
> Indeed, which cannot be right: both R5RS and R6RS require that the result
> be rational.
So, concretely, what should the behaviour of rationalize be for these
It seems to me that both situations should probably be an error.
"The process of preparing programs for a digital computer
is especially attractive, not only because it can be economically
and scientifically rewarding, but also because it can be an aesthetic
experience much like composing poetry or music."
-- Donald Knuth
Scheme-reports mailing list