> On Jan 25, 2017, at 10:03, Xiaodi Wu via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> Stephen Canon wrote that Arithmetic should refine ExpressibleByIntegerLiteral
> because of certain mathematical properties of rings. In that case, 0 and 1
> would just be spelled in that way. Otherwise, +1.
>> On Wed, Jan 25, 2017 at 11:38 Anton Mironov via swift-evolution
>> <swift-evolution@swift.org> wrote:
>> Hi everyone,
>>
>> I want to suggest a tiny extension to an Arithmetic protocol. It would be
>> nice to have an additive identity and a multiplicative identity constants.
>> Basically zero and one.
>>
>> ```
>> protocol Arithmetic {
>> /* ... */
>> static var zero: Self { get } // additive identity: (value + .zero) ==
>> value
>> static var one: Self { get } // multiplicative identity: (value * .one)
>> == value
>> }
>> ```
>>
>> These constants will ease implementation of math structures: vectors,
>> matrices and etc.
>> I’m sorry if I’m duplicating someone’s suggestion. It is really hard to
>> search for something in a long thread.
There is some merit in having them be declared as static properties... If it's
a non-trivial process to initialize a type, it might be worth it to have a
static property that either provides the storage directly or just returns a
fileprivate value declared outside the type.
- Dave Sweeris
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