On Jun 5, 2016, at 8:24 PM, T.J. Usiyan via swift-evolution <[email protected]> wrote: > Sub typing is the answer that we're going with then?
Most likely. At this point, we’re not really accepting additive changes to Swift 3 anyway, so any proposal would need to wait until post-swift 3 in any case. Plans for releases beyond Swift 3 haven’t been made yet - the metaplan is to come up with a plan in ~August timeframe. -Chris > On Sat, Jun 4, 2016 at 4:26 PM, T.J. Usiyan <[email protected] > <mailto:[email protected]>> wrote: > It could be a more general solution. I am unclear about what 'subtype > relationships' means here though. > > Are you talking a about what you allude to here? > https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151130/000525.html > > <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151130/000525.html> > > > The benefit of explicitly narrowing, in my opinion, is that there is no > unnecessary cost to figuring out lookup. (Please correct me if I am > mistaken.) Implicit promotions introduce uncertainty with regard to what a > value is being treated as in any given moment. This uncertainty is worth it > in many cases but I will suggest that it is not worth it when trying to deal > with a narrower set of cases from an already established set. For example, in > the graph/lattice situation, conversions must be written because there is no > reasonable conversion that can be assumed. In this proposal, the conversion > is obvious and trivial because the relationship is completely clear. > > All of that said, I *am* unclear about what subtype relationships means so it > may very well be a better solution. It certainly sounds like a more general > solution but I am not convinced that that is an advantage when trying to deal > with a strict subset. > > TJ > On Sat, Jun 4, 2016 at 1:25 AM, Chris Lattner <[email protected] > <mailto:[email protected]>> wrote: > >> On Jun 3, 2016, at 2:35 PM, T.J. Usiyan via swift-evolution >> <[email protected] <mailto:[email protected]>> wrote: >> >> Since this seems to have some interest, I've made a gist. >> >> https://gist.github.com/griotspeak/963bc87a0c244c120264b11fb022d78c >> <https://gist.github.com/griotspeak/963bc87a0c244c120264b11fb022d78c> > We have frequently discussed introducing subtype relationships between > structs and enums, in an effort to allow limited implicit promotions (e.g. > from small integers to wider integers). Wouldn’t that be a more general > solution to this same problem? > > -Chris > > > > _______________________________________________ > swift-evolution mailing list > [email protected] > https://lists.swift.org/mailman/listinfo/swift-evolution
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