The floating-point API design looks great. However, I'm concerned about providing a generic Arithmetic protocol:
> On Apr 14, 2016, at 4:55 PM, Stephen Canon via swift-evolution > <swift-evolution@swift.org> wrote: > > A new protocol, Arithmetic, is introduced that provides the most basic > operations (add, subtract, multiply and divide) as well as Equatable and > IntegerLiteralConvertible, and is conformed to by both integer and floating- > point types. > > There has been some resistance to adding such a protocol, owing to > differences in behavior between floating point and integer arithmetic. While > these differences make it difficult to write correct generic code that > operates on all "arithmetic" types, it is nonetheless convenient to provide a > single protocol that guarantees the availability of these basic operations. > It is intended that "number-like" types should provide these APIs. There are many other things we could do because they're "convenient", but we don't because they're wrong or mislead users into design cul-de-sacs. For example, we could provide integer indexing into strings, which would certainly be convenient, but we don't do that because it would lead to misguided accidentally-quadratic algorithms all over the place. This feels like a similar accommodation—while convenient, it makes it too easy for users to write naive real-number-arithmetic code and apply it blindly to numeric representations with very different error and overflow behavior. By including "divides" in the protocol, you're also implying a common abstraction over two *completely different* operations—integer quotient and floating-point division don't share many properties other than unfortunately sharing an operator in C. -Joe _______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution
