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

[Dave Abrahams]

on Wed Feb 17 2016, Radosław Pietruszewski <swift-evolution at swift.org> wrote:

> +1. Like others, this was one of the first stdlib extensions I’ve put
> into my Swift projects. It’s very common to want to find the first
> matching element in an array (or, perhaps even more common, find what
> you know if the only matching element — `filter` without the extra
> step of unpacking the value from array.)
>
> It’s also common in other languages, and `find` is a good name.

My only hesitation is that find has the strong connotation of not
modifying the underlying sequence, but any single-pass sequence will be
consumed.  I don't know why that should bother me, though, considering
the many other such methods we have defined on SequenceType.

>
> — Radek
>
>> On 30 Dec 2015, at 03:38, Kevin Ballard via swift-evolution <swift-evolution at swift.org> wrote:
>> 
>> I'm proposing a new extension method on SequenceType called find(). It's similar to CollectionType.indexOf() except it returns the element:
>>  
>> extension SequenceType {
>>     /// 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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-- 
-Dave