Re: [Json] Minus Zero

[Anders Rundgren <[e-mail]>]

On 2016-06-21 22:41, John Cowan wrote:
> Anders Rundgren scripsit:
>
>> Apparently the ES6 folks consider IEEE 0.0 and -0.0 equal during JSON
>> serialization.
>
> In effect that means that -0, like NaN and Infinity and -Infinity, can't
> be serialized correctly as JSON.  But instead of being serialized as null,
> it's serialized the same as 0.

I would have done the same.  -0.0 is as I understand as close to zero you can get.
The need for separating the -0.0 and 0.0 in real-world applications is probably 0.0 :-)

If full IEEE notation is needed "string" representation seems to be the only way ahead.

>> In order to make anything else JSON would need separate integer and
>> floating point types.
>
> I don't understand that.  JavaScript's internal model of numbers already
> includes -0.0 (e.g. the value of the expression 1/(-1*0) is -Infinity).
> The node.js and Chrome REPLs will print -0 in appropriate circumstances
> (whereas the Rhino and Edge REPLs will not).

I just referred to the fact that -0 is not a useful way of serializing an integer,
it only makes (some) sense in an IEEE floating point world.

By using a single type for holding "Number", the designers had to do some compromises.

In my java-based JSON parser I have added additional checks so that if you expect an
integer using a getInt() access method, "19.0" would generate an exception.  Serializing
integers above abs((2**53)-1) also generates an exception.

Anders