2009/6/23 Brendan Eich <[email protected]> > On Jun 23, 2009, at 12:18 AM, Christian Plesner Hansen wrote: > > I've been looking around on the web for reasons why decimal arithmetic > should be added to ES. The most extensive page I could find was > http://speleotrove.com/decimal/decifaq.html. If anyone know other > good sources of information about decimal and its inclusion in ES > please follow up. > > > Mike Cowlishaw's pages on decimal have lots of arguments for it: > > http://www2.hursley.ibm.com/decimal/decifaq.html > http://www2.hursley.ibm.com/decimal/ >
I'm afraid both these links seem to have broken. > <http://www2.hursley.ibm.com/decimal/> > > The most-duplicated JS bug in bugzilla.mozilla.org is > > https://bugzilla.mozilla.org/show_bug.cgi?id=5856 > > Here's a typical naive JS user complaining that his computer his broken > because it can't calculate correct differences: > > "... I typed in: > > 9533.24-215.10 > > … and here is the garbage Apple babbled back at me: 9318.139999999999" > > He blamed Apple. Naive users often blame hardware for software bugs. > > > The strongest argument seems to be financial: binary arithmetic is > approximate in a way that makes it unsuitable for financial > calculations. I buy this argument in general -- I would definitely > want my bank to use some form of decimal arithmetic rather than binary > -- but less so in the context of ES. > > > Do you consider that naive user's calculator example to be "financial"? I > do not. > > The problem is worse for non-experts. The experts can cope. > > Anyway, decimal is not being pushed into JS at this point. At the last > face-to-face TC39 meeting, we changed direction to explore generalizing > value type support (including operators and literals if we can) so that > libraries could add first class number-like types. > > Whether any new value type would be native or self-hosted, and whether it > would be included in the core standard, are issues we want to defer until > later, ideally until there are de-facto standards to codify. > > The counter-argument articulated at the meeting by Sam was that it's rare > for users to download binary extensions to JS for browsers (Flash is the > only exception, and it's not primarily a JS extension). So users won't get > decimal unless it is part of the normative core spec, so the usability bug > reported as Mozilla bug 5856 won't get fixed. > > I think Sam has a point; lack of a standard could be a problem. But > whatever we do about it, the committee agreed to work on value types first. > They're on the Harmony agenda. > > /be > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > >
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