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

Dave Abrahams dabrahams at apple.com
Sun Feb 14 10:27:09 CST 2016 

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.

> 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.

>
> 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
>>> 
>>> _______________________________________________
>>> swift-evolution mailing list
>>> 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>
>> _______________________________________________
>> swift-evolution mailing list
>> swift-evolution at swift.org
>> https://lists.swift.org/mailman/listinfo/swift-evolution
>

-- 
-Dave

More information about the swift-evolution mailing list