[swift-evolution] ed/ing, InPlace, Set/SetAlgebra naming resolution

Dave Abrahams dabrahams at apple.com
Sun Feb 14 14:48:38 CST 2016 

on Sun Feb 14 2016, Tyler Fleming Cloutier <cloutiertyler-AT-aol.com> wrote:

>> On Feb 14, 2016, at 8:27 AM, Dave Abrahams <dabrahams at apple.com> wrote:
>> 
>> 
>> on Sat Feb 13 2016, Tyler Fleming Cloutier <cloutiertyler-AT-aol.com> wrote:
>> 
>>> I would, personally, be very careful about discarding the mathematical
>>> terms since they are so widely used and understood.
>> 
>> IMO it's better to leave them aside than to use them in “creative” ways
>> that might be misleading.
>> 
>
> Agreed. I’m all for that.
>
>>> One issue is that it’s going to be hard to search for the operation I
>>> want considering I won’t be looking for "func
>>> invertingMembershipOfContentsOf(other: Self) -> Self”. I’m concerned
>>> people are going to have to do mental gymnastics to build the map from
>>> math term to Swift function every time they want to look for a set
>>> operation method. “func invertingMembershipOfContentsOf(other: Self)
>>> -> Self” doesn’t exactly seem to fit in the commonly held Venn diagram
>>> mental model of set operations. You could always have a documentation
>>> comment that specifies the mathematical term so that people didn’t
>>> have to double check themselves every time.
>>> 
>>> That being said, if the autocomplete issue is not a concern, I’m of
>>> the opinion that the names Ricardo proposed are short, clear, and are
>>> not so hard to fit to my Venn diagram mental model.
>> 
>> +1
>> 
>>> However, I tend to think that if there has to be this much dancing to
>>> name a set of fundamental operations, the guidelines aren’t
>>> accomplishing their goal. 
>> 
>> I can't disagree.
>> 
>>> It’s going to make it that much harder for people do design their own
>>> APIs. I'm having quite a time trying to conform Mattt’s Surge API to
>>> the guidelines.
>> 
>> Please explain in detail.  Without details we don't know what's wrong
>> with the guidelines.
>
> Ah, I apologize. I’ve gone into detail about this API on the list
> before, but I should have included the details here.
>
> Here are my previous posts:
> https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160118/007560.html
> <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160118/007560.html>
>
> Basically the issues come down to the following. The Accelerate
> framework typical operates in a non-mutating way. This means that my
> API only has non mutating member functions and I should use the ed/ing
> rule according to the guidelines to name my methods.
>
> This is very difficult for some methods. I’m able to frequently get
> around the problem for things like “sin” or “arctan” by keeping them
> as global functions, but I can’t do that for a number of
> methods. Consider:
>
> remainder
> dot (returns a scalar, thus there can’t be a mutating version, so
> should I just call it dot? Guidelines don’t really comment on this)
> mean (same as above)
> cross
> reciprocal
> threshold
> copysign
> fastFourierTransform
> pow (arguably the method version should be called raisedTo)
>
> I could force all these to be global functions only, but these are not
> as cut and dry as “sin” or “arctan”. I feel like I’d be splitting my
> API up into two parts just based on the fact that it’s difficult to
> use the ed/ing rule. That makes it very difficult for users to find
> certain functions in my API.
>
> In this case there are no corresponding mutating operations because of
> the way Accelerate works, but one could certainly imagine an API with
> mutating counterparts. The way I read the guidelines, they seem to
> imply I should use ed/ing regardless of whether there is a mutating
> counterpart. I’d love to hear your thoughts on this.

As long as the ones without side effects read as noun phrases and the
ones with side-effects read as verb phrases, you're good.  No ed/ing
needed.


>
>
> Thanks,
>
> Tyler
>
>> 
>>> 
>>> Tyler
>>> 
>>>> On Feb 13, 2016, at 9:09 PM, Ricardo Parada via swift-evolution <swift-evolution at swift.org> wrote:
>>>> 
>>>> Hi Dave,
>>>> 
>>>> I would be okay with staying away from the mathematical terms
>>>> similar to what you are suggesting except that the union can still
>>>> be made more concise if you use merged / merge for the base name and
>>>> shorten the labels to a bare minimum without loosing clarity.  In
>>>> addition, the merge can have a second parameter with a default to
>>>> false in order to implement the symmetric difference
>>>> (a.k.a. exclusive or).  Recall that symmetric difference is the
>>>> union of two sets and then removing the intersection (or members in
>>>> common).  I think it looks perfect (concise and clear).  What does
>>>> everybody else think?
>>>> 
>>>> Non-mutable
>>>> 
>>>> let union = 			a.merged(with: b)
>>>> let intersection = 		a.members(in: b)
>>>> let difference = 		a.removingMembers(in: b)
>>>> let symmetricDifference = 	a.merged(with: b, removingMembersInCommon: true)
>>>> 
>>>> Mutable (In-Place)
>>>> 
>>>> a.merge(with: b)		// union in-place
>>>> a.removeMembers(notIn: b)	// intersect in-place
>>>> a.removeMembers(in: b)		// difference in-place
>>>> a.merge(with: b, removeMembersInCommon: true)	// symmetric difference in-place
>>>> 
>>>> Ricardo Parada
>>>> 
>>>> 
>>>>> On Feb 13, 2016, at 1:16 PM, Dave Abrahams via swift-evolution
>>>>> <swift-evolution at swift.org <mailto:swift-evolution at swift.org>>
>>>>> wrote:
>>>>> 
>>>>> 
>>>>> on Fri Feb 12 2016, Ricardo Parada <swift-evolution at swift.org
>>>>> <mailto:swift-evolution at swift.org>> wrote:
>>>>> 
>>>>>> Hi all,
>>>>>> 
>>>>>> I can’t make up my mind.  Let me propose two different alternatives
>>>>>> that I’m not sure if they have been considered:
>>>>>> 
>>>>>> ALTERNATIVE 1
>>>>>> 
>>>>>> Non-mutable (noun-based)
>>>>>> 
>>>>>> -  func union(other: Self) -> Self
>>>>>> +  func union(other: Self) -> Self		Assumes union is a noun, i.e. not a verb
>>>>>> 
>>>>>> -  func intersect(other: Self) -> Self
>>>>>> +  func intersection(other: Self) -> Self
>>>>>> 
>>>>>> -  func subtract(other: Self) -> Self
>>>>>> +  func subtraction(other: Self) -> Self
>>>>>> 
>>>>>> -  func exclusiveOr(other: Self) -> Self
>>>>>> +  func symmetricSubtraction(other: Self) -> Self
>>>>>> 
>>>>>> Mutable (verb-based)
>>>>>> 
>>>>>> -  mutating func unionInPlace(other: Self)
>>>>>> +  mutating func unite(other: Self)
>>>>>> 
>>>>>> -  mutating func intersectInPlace(other: Self)
>>>>>> +  mutating func intersect(other: Self)
>>>>>> 
>>>>>> -  mutating func subtractInPlace(other: Self)
>>>>>> +  mutating func subtract(other: Self)
>>>>>> 
>>>>>> -  mutating func exclusiveOrInPlace(other: Self)
>>>>>> +  mutating func symmetricSubtract(other: Self)
>>>>>> 
>>>>>> Comments: 
>>>>>> 
>>>>>> With this alternative we keep the union name which I assume is
>>>>>> popular.  However, one has to accept unite as a verb (for the mutable
>>>>>> version) as I wanted all the mutable methods use verbs for
>>>>>> consistency.  I think unite is acceptable because it can be found in
>>>>>> the dictionary and it is a verb.
>>>>>> 
>>>>>> Notice that all the non-mutable methods use nouns: union,
>>>>>> intersection, subtraction and symmetricSubtraction.
>>>>>> 
>>>>>> I understand some may oppose to symmetricSubtraction saying that
>>>>>> symmetricSubraction is not as common as "exclusive or".  However,
>>>>>> using symmetricSubtraction is consistent with subtraction and it hints
>>>>>> to a variation of the “subtraction" operation.  We will get used to it
>>>>>> quickly / easily.
>>>>>> 
>>>>>> The mutable methods all use verbs:  unite, intersect, subtract and symmetricSubtract.
>>>>>> 
>>>>>> ALTERNATIVE 2
>>>>>> 
>>>>>> Non-mutable
>>>>>> 
>>>>>> -  func union(other: Self) -> Self
>>>>>> +  func adding(other: Self) -> Self
>>>>>> 
>>>>>> -  func intersect(other: Self) -> Self
>>>>>> +  func intersecting(other: Self) -> Self
>>>>>> 
>>>>>> -  func exclusiveOr(other: Self) -> Self
>>>>>> +  func exclusiveOring(other: Self) -> Self
>>>>>> 
>>>>>> -  func subtract(other: Self) -> Self
>>>>>> +  func removing(other: Self) -> Self
>>>>>> 
>>>>>> Mutable
>>>>>> 
>>>>>> -  mutating func unionInPlace(other: Self)
>>>>>> +  mutating func add(other: Self)
>>>>>> 
>>>>>> -  mutating func intersectInPlace(other: Self)
>>>>>> +  mutating func intersect(other: Self)
>>>>>> 
>>>>>> -  mutating func exclusiveOrInPlace(other: Self)
>>>>>> +  mutating func exclusiveOr(other: Self)
>>>>>> 
>>>>>> -  mutating func subtractInPlace(other: Self)
>>>>>> +  mutating func remove(other: Self)
>>>>>> 
>>>>>> Comments: This alternative gives up on union in favor or add.  Many
>>>>>> may not like this, that is why I have it as the second alternative.
>>>>>> It brings back exclusiveOr and treats it as a verb.  Some may argue
>>>>>> that exclusiveOr is a noun for the "exclusive or" operation.
>>>>> 
>>>>> If we are going to force Set fit the naming guidelines, I would prefer
>>>>> to stay away from the mathematical terms altogether.
>>>>> 
>>>>>  func insertingContentsOf(other: Self) -> Self                 // union
>>>>>  mutating func insertContentsOf(other)
>>>>> 
>>>>>  func members(in other: Self) -> Self                           // intersection
>>>>>  mutating func removeMembers(notIn: other)
>>>>> 
>>>>>  func removingMembersAndAddingNonMembers(in other: Self) -> Self // symmetric difference
>>>>>  mutating func removeMembersAndAddingNonMembers(in other: Self)
>>>>> 
>>>>>  func removingMembers(in other: Self) -> Self                    // subtract
>>>>>  mutating func removeMembers(in other: Self)
>>>>> 
>>>>> If it would help with clarity, we could replace "in" with "foundIn"
>>>>> above.
>>>>> 
>>>>> -- 
>>>>> -Dave
>>>>> 
>>>>> _______________________________________________
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>>>>> swift-evolution at swift.org <mailto:swift-evolution at swift.org>
>>>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>>>> <https://lists.swift.org/mailman/listinfo/swift-evolution>
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>>> 
>> 
>> -- 
>> -Dave
>

-- 
-Dave

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