[swift-evolution] Pitch: Support for map and flatMap with smart key paths

Max Moiseev moiseev at apple.com
Fri Jun 9 18:06:55 CDT 2017

Sorry. I might be missing something. Why is this better than:

let allEmployees = Set(managers.flatMap { $0.directReports }


> On Jun 7, 2017, at 10:35 AM, Adam Sharp via swift-evolution <swift-evolution at swift.org> wrote:
> The new smart key path feature is really lovely, and feels like a great addition to Swift.
> It seems like it might be straightforward to add overloads of `map` and `flatMap` to the standard library to make use of the new functionality:
> 	let managers = flatOrganisation.managers
> 	let allEmployees = Set(managers.flatMap(\.directReports))
> 	let employeeNames = Set(allEmployees.map(\.name))
> This feels like a really natural way of working with key paths in a functional style. It makes a lot of sense for collections, and possibly for Optional too (although as far as I can see optional chaining is more or less equivalent, and with more compact syntax).
> I’m hoping that this might be low-hanging fruit that could be considered for the Swift 4 release. I’d be happy to have a go at writing a proposal if there’s interest!
> –Adam
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