On Wed, Sep 17, 2008 at 6:50 PM, Maciej Stachowiak <[EMAIL PROTECTED]> wrote:
> > > I agree that typeof 1.5m == typeof 1.1m. However, I do not agree that 1.1m > == 1.1. These should be !=, since they represent distinct real numbers. > > > It seems to me that Brendan said 1.1m != 1.1 and did not question this. > Brendan, please correct me if I misrepresent your argument. I took Brendan to be saying that 1) If typeof 1.1m were 'number' then we'd be obligated to have 1.1m == 1.1. 2) We want 1.1m != 1.1. 3) Therefore, typeof 1.1m must not be 'number'. I disagree with #1 and thus #3. > > I do agree that 1.5m == 1.5, but only because they represent the same real > number, not because they look the same. This extends the notion of cohort > across the decimal/binary divide. > > -0, 0, -0m, 0m, 0.000m > > may all be computationally distinct values. (Is 0.00m distinct from 0m?) If > they are, then they should therefore be distinguished by any > Object.identical() and Object.indentityHash() operations. But they all > represent the same real number, so they should be ==. If we agree that they > should also all be typeof 'number', then they should also all be === and be > considered generalized cohorts. > > > Brendan's premise is that 1.5m has different operational behavior from 1.5 > and therefore it would be wrong to make them '==='. I tend to agree. Making > '===' treat distinct values the same and then introducing a new > Object.identical to tell the difference seems inelegant. > -0 has a different operational behavior than 0. Ok, we've got one weird one. I could live with that as an exception to a general rule. However, with the introduction of decimal, we've got cohorts galore. 1.1m has a different operational behavior than 1.1000m, but we've agree they should be ===. With the introduction of decimal, === no longer approximates a test of operational equivalence, and we still need such a test. > > > > If typeof all these were 'number', then binary and decimal could share a > single NaN, Infinity, and -Infinity. Only the remaining finite numeric > values would be distinctly either binary or decimal. > > I agree with Sam and apparently Crock and everyone else that mixed mode > should coerce to decimal. Or, at least, I have no objection to that > position. > > > If that is the case then 1.5m / 10.0 != 1.5 / 10.0, and thus it seems wrong > for 1.5m and 1.5 to be '==='. > 0/-0 != 0/0. Does it thus seem wrong that -0 === 0? Well, yes, actually it does seem wrong to me, but we all accept that particular wrongness. This is just more of the same. > > Were we to adopt this, then I think "use decimal" should condition only > whether an unqualified numeric literal be interpreted as binary or decimal > floating point. We should then have a suffix which means binary floating > point, so you can say it explicitly. Nothing else about the numerics should > be conditioned by the pragma. > > > Perhaps that suffix could be 'f' as in C/C++. > > I think that's better than 'd'. But it's confusing in a different way: decimal floating point is still a floating point just as much as binary floating point is. I have no letter to suggest. -- Cheers, --MarkM
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