Are there common languages where -0 != +0? Or are you implying that this would be a good decision when creating a new language?

javascript:

    > 1/(-0)
    -Infinity
    > 1/0
    Infinity
    > Object.is(0, -0)
    false

Of course = doesn't actually test equality in javascript. == reports -0 as being equal to +0, but Object.is reports them as different.

See now, I contest this particular defense because it groups together 'javascript' and 'good decision'.

basically every language with IEEE-754[1] compliance..!

[1] - https://en.m.wikipedia.org/wiki/IEEE_754

I'd think that in all those languages, -0 == +0 tests true, though. In JavaScript even -0 === +0 tests true.

The only way to tell them apart in general is to divide by them. In some languages you might be able to type-pun and examine the bit pattern, or do things like Object.is() or whatnot.

But only when imposing a total ordering.

that’s not the case, in IEE754 floating point, zero is signed - i.e negative and positive zero are distinct values

But the standard comparison operators don’t distinguish them.