You'll have to forgive my ignorance on the matter because I'm also not a type checker expert. If compile-time performance concerns are the motivating factor, is it possible to address them in a different way that would not require trampoline code or public interface bloat, like hoisting operators into static protocol methods? Presumably then `lhs + rhs` for two T's conforming to FloatingPoint would map directly to `T.+(_ lhs: T, _ rhs: T)` and the concrete global overloads could still be omitted?
On Tue, Apr 26, 2016 at 11:44 AM Chris Lattner <[email protected]> wrote: > > > On Apr 26, 2016, at 11:42 AM, Chris Lattner via swift-evolution < > [email protected]> wrote: > > > > On Apr 26, 2016, at 8:47 AM, Tony Allevato via swift-evolution < > [email protected]> 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. > > Also, sorry for not being explicit about this. I’m not a type checker > expert, but I believe that using operator requirements imposes the same > load on the type checker as having large overload sets. > > -Chris
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