[swift-evolution] Proposal: Add function SequenceType.find()

[Kevin Ballard]

Alternatively you can write

subviews.lazy.flatMap({ $0 as? NSButton }).find({ $0.state ==
NSOnState })

-Kevin Ballard

On Wed, Feb 17, 2016, at 07:12 AM, Maximilian Hünenberger via swift-evolution wrote:
>
> I think
>
> subviews.find{ ($0 as? NSButton)?.state == NSOnState } as? NSButton
>
> is sufficient and makes it clear that you are searching for a specific
> type. Even though you have to cast twice I don't think an additional
> method would be worth its use since it isn't used as often.
>
> - Maximilian
>
> Am 17.02.2016 um 10:32 schrieb Marco Masser via swift-evolution <swift-
> evolution at swift.org>:
>> I just saw this PR and have a quick comment about the implementation:
>> It could be shortened by a few lines using a where clause like this:
>>
>> func find(@noescape predicate: Self.Generator.Elementthrows -> Bool)
>> rethrows -> Self.Generator.Element? { for element inselfwheretry
>> predicate(element) { return element    } returnnil }
>>
>>
>> Also, I’d like suggest adding a variant that works better with
>> heterogenous sequences, but I’ll raise that when this proposal goes
>> into review.
>>
>> FYI: That variant would look like this: func find<T>(_: T.Type,
>> @noescape matching predicate: Tthrows -> Bool) rethrows -> T?
>>
>> A question by me on the swift-users mailing list describes its
>> intention, implementation, and usage: [swift-users] Which is the more
>> idiomatic approach for pinning down  the type of a generic
>> parameter?[1]
>>
>> Cheers,
>>
>> Marco
>>
>>
>>> On 2016-01-10, at 01:58, Kevin Ballard via swift-evolution <swift-
>>> evolution at swift.org> wrote:
>>>
>>> Proposal PR submitted as
>>> https://github.com/apple/swift-evolution/pull/94
>>>
>>> -Kevin Ballard
>>>
>>> On Tue, Dec 29, 2015, at 06:38 PM, Kevin Ballard wrote:
>>>> I'm proposing a new extension method on SequenceType called find().
>>>> It's similar to CollectionType.indexOf() except it returns the
>>>> element:
>>>>
>>>> extensionSequenceType { /// Returns the first element where
>>>> `predicate` returns `true`, or `nil` /// if such value is not
>>>> found. public func find(@noescape predicate:
>>>> (Self.Generator.Element) throws -> Bool) rethrows ->
>>>> Self.Generator.Element? { for elt in self { if try predicate(elt) {
>>>> return elt            }        } return nil    } }
>>>>
>>>> -Kevin Ballard
>>>>
>>>
>>>
>>> _______________________________________________
>>> swift-evolution mailing list swift-evolution at swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>> _______________________________________________
>> swift-evolution mailing list swift-evolution at swift.org
>> https://lists.swift.org/mailman/listinfo/swift-evolution
> _________________________________________________
> swift-evolution mailing list swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution



Links:

  1. https://lists.swift.org/pipermail/swift-users/Week-of-Mon-20160118/000893.html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-evolution/attachments/20160217/93248d09/attachment.html>