Re: [racket-users] Defining algebraic data types?

That makes perfect sense, thank you. On Tuesday, February 6, 2018 at 12:43:07 AM UTC+1, Sam Tobin-Hochstadt wrote: > The problem is that the definition of `(Dual-Number N)` includes `N`, > and therefore > > (Dual-Number (Dual-Number String)) might either be a (D (D "x" "y") (D > "x" "y")) or

Re: [racket-users] (number->string -nan.0) == "+nan.0" ?

Thanks Norman. Sorry for not being as clear as I might wish. I was trying to provide an example suggesting significance divided by difficulty often influences the design of programming languages and libraries. For me the critique of the standard is context for the last sentence. The interesting

Re: [racket-users] (number->string -nan.0) == "+nan.0" ?

Greetings. On 6 Feb 2018, at 13:00, ben.rudgers wrote: "The library [math.h] doesn't try to distinguish +0 from -0. IEEE 754 worries quite a bit about this distinction. All the architectures I mentioned above can represent both flavors of zero. But I have trouble accepting (or even

[racket-users] Re: (number->string -nan.0) == "+nan.0" ?

The question reminded me of a passage in Plauger's *The Standard C Library* (1992): "The library [math.h] doesn't try to distinguish +0 from -0. IEEE 754 worries quite a bit about this distinction. All the architectures I mentioned above can represent both flavors of zero. But I have

Re: [racket-users] (number->string -nan.0) == "+nan.0" ?

Huh. Okay, thanks. On Mon, Feb 5, 2018 at 6:46 PM, Ben Greenman wrote: > Looks like its for the same reason that (number->string -0) yields "0". > > +nan.0 is special, but -nan.0 is the same as (- +nan.0) > > http://docs.racket-lang.org/reference/numbers.html > >

RE: [racket-users] (number->string -nan.0) == "+nan.0" ?

(eq? +nan.0 -nan.0) -> #t This is documented: The datum -nan.0 refers to the same constant as +nan.0, and -nan.f is the same as +nan.f. Jos _ From: racket-users@googlegroups.com [mailto:racket-users@googlegroups.com] On Behalf Of David Storrs Sent: martes, 06 de febrero de 2018 00:42

Re: [racket-users] (number->string -nan.0) == "+nan.0" ?

Not sure there should be a -nan.0 to start with. NaN is an absorbing value that shouldn't have a sign. I suspect it's because the + is a convenience to trigger the number reader, and then an appeal to symmetry and analogy to +inf.0 led to -nan.0? On Mon, Feb 5, 2018 at 11:46 PM, Ben Greenman