[swift-evolution] What about renaming Optional.map to Optional.mapMe ?

[Jay Zhao]

Hi Derrick,

Not just for optional array, but for all optional types. Optional.map has a deep confusion for we’re not sure what is $0 inside. And it is so commonly used compared to the collection of collection scenario mentioned by Alexis Beingessner.

- Jay Zhao

> On 7 Dec 2016, at 10:58, Derrick Ho <wh1pch81n at gmail.com> wrote:
> 
> Jay, I fail to see the point you are trying to make.  Can you clarify why we need a new map method for an optional array of elements?
> 
> On Tue, Dec 6, 2016 at 9:46 PM Jay Zhao via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> It applies in theory to think Optional as a collect of one and for that reason map is a perfect name.
> 
> But in practice, we often use the same variable name for array and array? .  So when you see :
> 		cars.map({...$0...})  
> You can not tell which map and even worse which $0 it is.
> 
> According to Swift API Design Guidelines #1, Clarity at the point of use. 
> And to combine theory and practice, I propose mapUnwrapped to remove the confusion.
> 
> Actually this is what’s been adopted in my company:
> 
> public extension Optional {
>     /// Pass the `Optional` into the closure that returns `Non-Optional`
>     public func mapUnwrapped<U>(_ transform: (Wrapped) throws -> U) rethrows -> U? {
>         return try map(transform)
>     }
> }
> 
> To summary my idea:
> This is the situation where usability > design purity for a language(a tool).
> 
> 
>> On 7 Dec 2016, at 08:05, Robert Widmann <devteam.codafi at gmail.com <mailto:devteam.codafi at gmail.com>> wrote:
>> 
>> If you think of Optional as a zero-or-one element collection there's really no reason this operation should be named any differently.  It still lifts a function over values to one over Optionals.  It still extracts the contents of the structure and applies the function (propagating failure if necessary).  The operation is no different from the one required of a plain Sequence conformance, why should it have a new name if it is not a new operation? 
>> 
>> ~Robert Widmann
>> 
>> 2016/12/05 22:46、Jay Zhao via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> のメッセージ:
>> 
>>> Hi there,
>>> 
>>> Code explains everything:
>>> 
>>> 	
>>> 
>>> /// Maybe a bad API naming in Swift? See below:
>>> 
>>>         /// array1 can be array of any object that have a `count` method
>>>         let array1 = [[String]]()
>>>         let array2 :[String]? = nil
>>>         
>>>         
>>>         // I believe the confusion between `array.map` and `optionalArray.map` is really bad.
>>>         // Because when you read code like this, you can not tell which is which:
>>>         _ = array1.map({$0.count})
>>>         _ = array2.map({$0.count})
>>>         
>>>         // It can be clearer:
>>>         // 1, we pass `self.element` into the closure
>>>         _ = array1.map({$0.count})
>>>         // 2, we pass self directly into the closure
>>>         _ = array2.mapMe({$0.count})
>>> 
>>> 
>>> The mapFlat method is also problematic.
>>> 
>>> Yours,
>>> Jay Zhao
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> 
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