I suspect that if there were an 'advanced' `map` it would largely eliminate `forEach` since a main use of `forEach` is because of limitation in map like multiple returns, combined map and filtering, etc.
The comment that you have to ignore a warning is however a valid point, perhaps like other languages, e.g. Java, you could have a `@suppress_unused_result_warning` annotation. Sent from my iPad > On 31 Dec 2015, at 9:41 PM, ilya via swift-evolution > <[email protected]> wrote: > > I like having separate forEach. As already said, forEach produces different > visual grouping of logic compared to for operator. It's especially useful if > you just pass a named function to it. > > forEach is also not the same as map: > > let block: Int -> Void = ... > [1,2,3].map(block) > > Here the result has the type [Void], not Void and the compiler correctly > produces a warning. We'd have to explicitly assign the result to silence it, > which now hides the fact that block wasn't producing anything in the first > place. > > This will hold true for any advanced variant of map. > > Ilya. >> On Thu, Dec 31, 2015 at 10:30 Dave Abrahams via swift-evolution >> <[email protected]> wrote: >> >> -Dave >> >>> On Dec 30, 2015, at 8:48 PM, Kevin Ballard via swift-evolution >>> <[email protected]> wrote: >>> >>> Swift didn't use to have forEach(). It was added fairly late, and I suspect >>> (though I don't actually know) that it was done so to appease people who >>> kept abusing map() for the same function, as well as the die-hard >>> everything-must-be-functional crowd. >> >> Those are two of the reasons. But the reason that put forEach over the line >> and convinced me to add it, just slightly, was syntactic: >> >> for x in some.very.long[chain] >> .of.map { $0 } >> .filter { something }.whatever { >> ... >> } >> >> reads "inside-out," like nested(free(function(calls())))) vs. >> >> some.very.long[chain] >> .of.map { $0 } >> .filter { something }.whatever >> .forEach { x in >> ... >> } >> >>> >>> Personally, I'd rather we didn't have it because it encourages people to >>> use it, but I suppose it's better to give people an appropriate tool than >>> to keep watching them abuse map(). >>> >>> -Kevin Ballard >>> >>>> On Wed, Dec 30, 2015, at 04:50 PM, Craig Cruden via swift-evolution wrote: >>>> I don’t see the benefit of taking a simple declarative expression (map, >>>> flatMap, filter) and turning it into a complicated imperative/iterative >>>> loop. You already have the ability to iterate through a set and do >>>> whatever you want to do with with whatever logic you want to use using. I >>>> would have no problem for the most part removing foreach - it is more of a >>>> convenience method for doing an iterative loop through a collection - and >>>> to be quite honest rarely use outside of maybe putting in a print >>>> statement temporarily in there (but more often just turn the resulting set >>>> into comma delimited output and printing it). >>>> >>>> >>>>> On 2015-12-31, at 5:10:22, Howard Lovatt via swift-evolution >>>>> <[email protected]> wrote: >>>>> >>>>> >>>>> You could replace `forEach` with a supped up `map` that also allowed >>>>> `break` and `continue`. The following library function gives `continue` >>>>> and `break` and also combines `repeat`, `times`, `forEach`, `filter`, >>>>> `flatMap`, and `map` into one: >>>>> >>>>> public final class MapController<E, R> { >>>>> var results = [R]() >>>>> >>>>> var isContinuing = true >>>>> >>>>> init<C: CollectionType where C.Generator.Element == E>(_ collection: C, >>>>> sizeEstimate: Int = 0, @noescape mapper: (controller: MapController<E, >>>>> R>, element: E) throws -> R?) rethrows { >>>>> results.reserveCapacity(sizeEstimate) >>>>> for var generator = collection.generate(), element = generator.next(); >>>>> element != nil && isContinuing; element = generator.next() { >>>>> let result = try mapper(controller: self, element: element!) >>>>> if let actualResult = result { >>>>> results.append(actualResult) >>>>> } >>>>> } >>>>> } >>>>> } >>>>> >>>>> extensionCollectionType { >>>>> /// Controllable `map`, additional controls beyond simple `map` are: >>>>> /// >>>>> /// 1. Continue without returning a result (`return nil`) >>>>> /// 2. Return multiple results (`control.results += [...]` then `return >>>>> nil`) >>>>> /// 3. Break (`control.isContinuing = false` then `return nil`) >>>>> /// >>>>> /// These additional controls allow this `map` to function like `repeat`, >>>>> `times`, `forEach`, `filter`, `flatMap`, and `map` combined into one as >>>>> well as providing an early termination (break). >>>>> @warn_unused_result func map<R>(sizeEstimate sizeEstimate: Int = 0, >>>>> @noescape mapper: (controller: MapController<Self.Generator.Element, R>, >>>>> element: Self.Generator.Element) throws -> R?) rethrows -> [R] { >>>>> return try MapController(self, sizeEstimate: sizeEstimate, mapper: >>>>> mapper).results >>>>> } >>>>> } >>>>> >>>>> // Demonstration of full functionality including continue, break, and >>>>> multiple returns >>>>> var result = (0 ..< 5).map { (control, index) -> Int? in >>>>> switch index { >>>>> case 1: >>>>> returnnil// Continue - skip 1 (`filter`) >>>>> case 2: >>>>> control.results.append(2) // Yield two results - this one and the >>>>> 'return’ yield (`flatMap`) >>>>> case 3: >>>>> control.isContinuing = false// Break after next yield - which >>>>> could be `return nil` if there are no more results >>>>> default: >>>>> break >>>>> } >>>>> return index // Yield next result - except for case 1 all the above yield >>>>> `index` >>>>> } >>>>> print(result) // prints `[0, 2, 2, 3]` note missing "1", double "2", and >>>>> last is "3" >>>>> >>>>> // Demonstration of `repeat`/`forEach`/`times` like usage - note `(_, _) >>>>> -> Void?` >>>>> result = [Int]() >>>>> (0 ..< 3).map { (_, _) -> Void? in >>>>> result.append(1) // Do whatever - in this case append to a global >>>>> returnnil// Don't yield any results >>>>> } >>>>> print(result) // prints `[1, 1, 1]` >>>>> >>>>> Would this be a superior alternative to both `forEach` and `times` in the >>>>> library and `repeat` as a language feature? >>>>> >>>>> Sent from my iPad >>>>> >>>>> _______________________________________________ >>>>> swift-evolution mailing list >>>>> [email protected] >>>>> https://lists.swift.org/mailman/listinfo/swift-evolution >>>> >>>> >>>> _______________________________________________ >>>> swift-evolution mailing list >>>> [email protected] >>>> https://lists.swift.org/mailman/listinfo/swift-evolution >>> >>> >>> _______________________________________________ >>> swift-evolution mailing list >>> [email protected] >>> https://lists.swift.org/mailman/listinfo/swift-evolution >> >> >> >> _______________________________________________ >> swift-evolution mailing list >> [email protected] >> https://lists.swift.org/mailman/listinfo/swift-evolution > > _______________________________________________ > swift-evolution mailing list > [email protected] > https://lists.swift.org/mailman/listinfo/swift-evolution
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