I agree on your point — base-10 notation is not compatible with a base-2 infrastructure. However, that is just exposing the reality of the floating point data type. It still does not answer my question on why we can’t just provide a decimal data type.
I am aware of the NSDecimalNumber class. But that is a layer on top of the core language, and not very performant relatively speaking - at least I would presume? Please correct me if I am wrong. -T.J. > On Sep 12, 2016, at 10:26, Jens Alfke <j...@mooseyard.com> wrote: > > >> On Sep 12, 2016, at 10:10 AM, Teej . via swift-users <swift-users@swift.org >> <mailto:swift-users@swift.org>> wrote: >> >> …in spite of the CPU’s quirks in handling floating point numbers in a >> maddening inaccurate manner. > > Well, in the CPU’s defense, it’s only inaccurate because the puny humans > insist on dividing their currency into fractions of 1/10, which has no exact > representation in binary. (Apparently this is an ancient tradition > commemorating the number of bony outgrowths on certain extremities of their > grotesque meat-bodies.) I could — I mean, the computers could — point out > that if we divided our currency units into 7 pieces, our precious decimal > numbers would quickly become inaccurate too. :) > >> Is there any particular reason why we do not have a native Decimal data >> type for Swift? > > Cocoa’s Foundation framework has an NSDecimalNumber class that provides > decimal numbers and arithmetic. The class docs for that include a note that > "The Swift overlay to the Foundation framework provides the Decimal > structure, which bridges to the NSDecimalNumber class. The Decimalvalue type > offers the same functionality as the NSDecimalNumberreference type, and the > two can be used interchangeably in Swift code that interacts with Objective-C > APIs." > > The question is whether this has been ported to the in-progress native Swift > foundation library yet. I haven’t checked. > > —Jens
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