[swift-evolution] [swift-evolution-announce] [Review] SE-0067: Enhanced Floating Point Protocols

Jordan Rose jordan_rose at apple.com
Wed Apr 27 11:10:56 CDT 2016

> On Apr 26, 2016, at 11:42, Chris Lattner via swift-evolution <swift-evolution at swift.org> wrote:
> On Apr 26, 2016, at 8:47 AM, Tony Allevato via swift-evolution <swift-evolution at swift.org> wrote:
>> That seems like a purely syntactic concern that could potentially be addressed in other ways, though. I'm not sure the choice of "duplicate all operators using verbosely-named methods" is the best one for the reasons I mentioned above, and the question of "how do we cleanly unify operators with other protocol requirements?" seems out-of-scope and orthogonal to this proposal.
> There is a strong motivation for this approach though: we want the type checker to be scalable.  John recently wrote an epic piece about why having tons of overloads is a really bad idea:
> https://lists.swift.org/pipermail/swift-dev/Week-of-Mon-20160404/001650.html
> It is *much* better for type checker performance to have (e.g.):
> func +<T : FloatingPoint>(lhs : T, rhs : T) -> T { return lhs.add(rhs) }
> func +<T : Integer>(lhs : T, rhs : T) -> T { return lhs.add(rhs) }
> Rather than overloads for 4 floating point types, and 8+ integer types.   We really need to eliminate all the “expression too complex” classes of issues, and this is an important cause of them.

That’s a reason to pull operators in as members, not push them out as second-class free functions.


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