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

[Marco Masser]

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.Element throws -> Bool) rethrows -> Self.Generator.Element? {
    for element in self where try predicate(element) {
        return element
    }
    return nil
}


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: T throws -> 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? <https://lists.swift.org/pipermail/swift-users/Week-of-Mon-20160118/000893.html>

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 <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
>>  
>  
> 
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